THANATOCHEMISTRY - FINAL
BASIC ANHYDRIDES (METALLIC OXIDES
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ACID - PROPERTIES
1. Acids in solution taste sour. 2. Acids change blue litmus to red. Litmus is a compound described as an acid-base indicator. Such a substance, which is one color in the presence of an acid and another color in the presence of a base, is used to experimentally distinguish between acids and bases. 3. Dilute acids react with metals above hydrogen in the electrochemical series, liberating hydrogen gas. 4. Acids react with bases to form water and a salt. This reaction is called neutralization. It is so named because by the reaction of an acid and a base, the hydrogen ion of the acid combines with the hydroxide ion of the base, forming water. In this way, the acidic nature (H+) of the acid is neutralized by the basic nature (OH-) of the base. For example: The driving force behind this neutralization reaction is the formation of water. Whenever the constituents of water, hydrogen ions and hydroxide ions are brought together in a reaction, water forms. In addition, in the reaction between hydrochloric acid and sodium hydroxide, the negative chloride ion from the acid joins with the positive ion from the base. The product sodium chloride is classified as a SALT. The definition of a salt is a compound formed between a positive ion other than hydrogen, and a negative ion other than hydroxide. Remember, neutralization reactions are double replacement reactions. 5. Acids react with carbonates and bicarbonate (hydrogen carbonate), liberating carbon dioxide and forming a salt. Carbonates are compounds in which the negative part is the ion CO3-. Bicarbonates are compounds in which the negative ion is HCO3-. The reaction between an acid and a carbonate or a bicarbonate can be broken down into two part. If sodium carbonate and sulfuric acid are reacted, the first step is a double-replacement reaction, the products being carbonic acid and sodium sulfate: CARBONIC ACID IS UNSTABLE AND WILL DECOMPOSE INTO CARBON DIOXIDE AND WATER. If an acid is accidentally spilled, sodium bicarbonate is sometimes poured on the area to neutralize the effects of the acid. Sodium bicarbonate is commonly called baking soda. It is used in baking along with an acidic substance to liberate carbon dioxide, which causes cakes and other baked goods to rise. 6. Acids react with sulfites forming sulfur dioxide and a salt. Sulfites are compounds that contain the ion SO3-2. As with carbonates, acids first react with sulfites, producing an unstable compound that then decomposes. The reaction between sulfuric acid and sodium sulfite is:
DISTILLATION
1. Distillation - This process represents the most efficient method of purifying Water. In addition to soluble solids, this process also removes insoluble solids and some bacteria. Gases with a lower boiling point than water, such as oxygen, carbon dioxide, ammonia, and chlorine, can not be removed.
LIQUEFACTION - GASES
1. Liquefaction - conversion of a solid or gas into a liquid form as a result of a physical or chemical change
PERCENTAGE
1. PERCENTAGE - This may be expressed as a percent by mass or a percent by volume. When formaldehyde gas is dissolved in water, the resulting solution, called FORMALIN, is 37% formaldehyde by mass and 40% formaldehyde by volume.
QUANTITATIVE TERMS
1. PERCENTAGE - This may be expressed as a percent by mass or a percent by volume. When formaldehyde gas is dissolved in water, the resulting solution, called FORMALIN, is 37% formaldehyde by mass and 40% formaldehyde by volume. 2. ppm - A unit that is frequently used to express very small concentrations. For instance, a typical carbon monoxide level in heavy smog is approximately 40ppm by volume. This means that if we have 1,000,000 parts 40 of them will be carbon monoxide. 3. RATIO - Some concentrations are expressed as the weight of solute to the weight of solution. A common concentration for the disinfectant HgCl2 is 1:1000. 4. INDEX - This term expresses the concentration of formaldehyde in an embalming fluid. The definition of index is the number of grams of pure formaldehyde gas in 100 milliliters of solution.
BASES - PROPERTY
1. Solutions of bases have a bitter, metallic taste. 2. Solutions of bases feel slippery. 3. Bases change red litmus to blue. If a few drops of the colorless indicator phenolphthalein are added to a base, the color changes to pink. 4. Bases react with acids forming salts and water. A neutralization that may not appear to fit the rules is that of aqueous ammonia, NH3, by an acid.
OXIDATION
1. The addition of oxygen to a substance. 2. The removal of hydrogen from a substance. 3. The removal of electrons from a substance. 4. The increase in oxidation number of a substance. When oxygen is added to a substance, that substance undergoes oxidation.
CONDENSATION - GASES
2. Condensation - a change of state of matter from a gas to a liquid.
FILTRATION
2. Filtration - This method consists of the physical removal of particle which are too large to pass through the pores in a filter. It is sometimes aided by the use of certain chemicals, which have the effect of building particles which are normally small enough to pass through the filter into substances large enough to be held back by the filter. Another method associated with filtration is called carbon adsorption or carbon filtration. Adsorption is a process in which certain substances adhere or stick to the surfaces of other substances. If a form of carbon called "activated charcoal" is used in conjunction with filters, gases and color can be removed from water.
PPM - PARTS PER MILLION
2. ppm - A unit that is frequently used to express very small concentrations. For instance, a typical carbon monoxide level in heavy smog is approximately 40ppm by volume. This means that if we have 1,000,000 parts 40 of them will be carbon monoxide.
BOILING
3. Boiling - This purification method has traditionally been used to remove bacteria from water. Most vegetative forms of bacteria are killed after five minutes of exposure to boiling temperatures. Boiling also removes gases and some soluble solids.
VAPORIZATION - GASES
3. Vaporization - the physical change from a liquid into a gas.
AERATION
4. Aeration - This process consists of spraying water into the air. It removes gases and oxidizable organic matter, which sometimes give an unpleasant odor or taste to water. Many wastewater treatment facilities use aeration as an intermediate step in purification of sewage.
INDEX
4. INDEX - This term expresses the concentration of formaldehyde in an embalming fluid. The definition of index is the number of grams of pure formaldehyde gas in 100 milliliters of solution.
CHLORINATION
5. Chlorination - Chlorine's ability to destroy odors and arrest putrefaction has been known since 1774. Chlorine and chlorine compounds have been the most widely used of the chemical disinfectants. They have universal application for treating both water supplies and wastewater effluent. Calcium hypochlorite has been widely used since 1908. It has an available chlorine content of about 35%, but loss occurs even when it is stored in tight drums. Except in emergencies the use of this compound has been abandoned owing to deterioration in quality, the complexity of equipment needed, the difficulty of preparation and application, odors produced, and its corrosive action. Relatively stable hypochlorite powders such as HTH and Perchloron, with available chlorine content of around 70% were subsequently developed. The widespread acceptance of chlorine as the disinfectant of choice in the purification of drinking water and wastewater appears to be due to its ability to maintain a residual. This constitutes an extra margin of safety in case of recontamination of purified water.
HYDRATES
5. Water will form HYDRATES - a compound in which there is a chemical union between water and certain substances when they crystallize. Plaster of Paris is an example of a hydrate:
BOILING POINT
A liquid boils at a temperature called the BOILING POINT, which is a physical property. At this temperature the vapor pressure of a liquid is equal to the pressure of the atmosphere on the liquid. When a substance boils, the atmosphere is actually pushed away by the vapor formed from the liquid. The atmospheric pressure determines the value of a liquid's boiling point. At one atmosphere pressure the boiling point is designated as the Normal Boiling Point. The normal boiling point of water is 100oC. If the pressure is less than one atmosphere, as on a mountain, the boiling point decreases. Under conditions of high pressure, such as a pressure cooker or an autoclave, boiling points are higher than normal. Food cooks faster in a pressure cooker because the increased pressure allows us to cook at a higher than normal temperature.
SOLUTE
A solute is the substance that is dissolved. It is usually the part of the solution that is present in a lesser amount. If a solute is to dissolve in a solvent, they must be similar in structure or in electrical properties.
SATURATED
A solution that contains all the solute the solvent can hold at a given temperature is described as SATURATED.
SOLVENT
A solvent is the substance that does the dissolving. It is usually the part of the solution that is present in a greater amount. In an aqueous solution, water is the solvent. In embalming fluids, the solvent is also called the VEHICLE.
CATALYSTS
A substance that speeds up a chemical reaction yet appears in unchanged form among the products of the reaction. All a catalyst does is increase the rate of the reaction. A catalyst increases the rate of the reaction by lowering the amount of energy necessary for the reaction to occur. CATALYSTS DO NOT CAUSE REACTIONS; THEY ALTER THE REACTION RATES.
ELECTROCHEMICAL SERIES
ALL ELEMENTS ABOVE HYDROGEN IN THE SERIES DISPLACE HYDROGEN FROM DILUTE ACIDS - ALL ELEMENTS BELOW HYDROGEN DO NOT DISPLACE HYDROGEN FROM DILUTE ACIDS. METALS DISPLACE HYDROGEN NOT ONLY FROM DILUTE ACIDS BUT ALSO FROM WATER. ACTIVITY SERIES OF METALLIC ELEMENTS Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Tin Lead HYDROGEN Copper Mercury Silver Platinum Gold
ARRHENIUS THEORY - ACIDS & BASES
ARRHENIUS THEORY - This theory states that ACIDS are substances that dissociate (break apart) in an aqueous solution to yield hydrogen ions. For example: The Arrhenius definition of a BASE is a substance that dissociates in an aqueous solution to yield hydroxide ions. For example: Arrhenius was not aware of the self-ionization of water. Today, we know that hydrogen ions do not exist alone in water. We think of them as being attracted to water molecules, forming hydronium ions (H3O+). A modification of the Arrhenius definition says acids dissociate in aqueous solutions to yield hydronium ions. Actually, because water self-ionizes, acids increase the hydronium-ion concentration of water. Likewise, bases increase the hydroxide-ion concentration of water.
SELF-IONIZATION OF WATER
Acids and bases are normally used dissolved in water. An important characteristic of water that relates to acids and bases is its self-ionization. As water molecules collide with one another, there is the possibility that a hydrogen ion from one water molecule will transfer to another water molecule. The polarity of water is the basis for this chemical change. We have already seen that the negative oxygen of one water molecule attracts the positive hydrogen of another. If the molecules collide forcefully, the positive hydrogen in the form of an ion can be pulled from its molecule.
ACID- STRENGTH
Acids are classified as strong, moderate, and weak. The strength of an acid is determined by its percent dissociation in aqueous solution. Acids yielding a relatively large number of hydrogen ions in solution are strong. When writing an equation for strong acids an arrow is used only in the forward direction showing the dissociation of the acid. If an acid yields a relatively small number of hydrogen ions in solution, it is weak. Acids may also be categorized as unstable.
NEUTRONS
All atoms with the exception of hydrogen contain neutrons. As the name implies these particles have no charge. They are neutral. Their mass is approximately the same as that of the proton. A function of the neutrons is to give the nucleus stability. In atoms with many protons, repulsions of the positive charges cause nuclear instability. Neutrons provide a buffering action by separating the positive charges from one another.
IONIC COMPOUNDS
All ionic compounds are polar.
CONJUGATE ACID-BASE PAIR
Ammonia (NH3) and the ammonium ion (NH4+) differ only by a proton. When the only difference between two substances is a proton, they are called a CONJUGATE ACID-BASE PAIR. The conjugate base of an acid is always determined by removing one proton from the acid. The conjugate acid of a base is the base plus a proton. WATER IS BOTH AN ACID & A BASE.
EVAPORATION
Another important property of liquids is evaporation from an open container. In a liquid the energy of each particle changes as it collides with other particles. When particles near the surface obtain enough energy to overcome the attractive forces between them, these surface particles change to the gaseous state. This transition from liquid to gas is referred to as EVAPORATION.
CRYSTALLOID
Another name for a true solution is a CRYSTALLOID. True solutions have the smallest particle size.
VISCOSITY
Another property that liquids exhibit is called VISCOSITY. Viscosity is the resistance that a liquid exhibits to the flow of one layer over another arising from the molecular attraction between the molecules of a liquid. The thicker a liquid is the higher its viscosity level. Syrup is more viscous than water.
COMBUSTION
Another word for burning is COMBUSTION.
AMPHOTERIC
Any substance that can act as either an acid or a base is
FREE RADICALS
As radiation travels through living tissue, the interaction may form highly reactive particles called free radicals. A free radical has an unpaired electron that causes it to continue to react after its formation. If these reactions occur in the nucleus of a cell, the molecules of the genes may be altered. Some of the effects could be death of the cell, formation of a malignant carcinoma, or transmission of a genetic mutation.
ELECTRONS
Atoms are composed of a small, dense, positively charged nucleus that is surrounded by one or more negatively charged particles.
MOLECULES
Atoms join together to form MOLECULES, which are the smallest units into which a compound may be divided and still retain the properties of that compound.
HYDROGEN BONDS
Attractive forces occur between the hydrogen on one water molecule and an oxygen on the other molecule. The attractive forces are called HYDROGEN BONDS.
BINARY ACIDS
Binary acids derive their names from the element other than hydrogen. Their names always begin with the prefix hydro and end with the suffix -ic.
COMPRESSIBILITY - GASES
COMPRESSIBILITY means that increasing the pressure on a gas may decrease the volume of a gas. You can decrease the size of a balloon by compressing it and the gas inside of it.
DELIQUESCENCE
Certain hydrates have the ability to absorb enough moisture from the air under ordinary atmospheric conditions to dissolve. The process is called DELIQUESCENCE. The word dissolve in this case, implies that the hydrate is a solid. Therefore, sulfuric acid, a liquid, may be described as hygroscopic but not deliquescent. Calcium chloride will dissolve when exposed to the air. Calcium chloride may be used as a de-icer. These substances are referred to as mold inhibitors rather than mold killers (fungicides).
GREEK LETTER DELTA
Chemist symbol for heat.
HYGROSCOPIC
Chemists use the term hygroscopic when referring to hydrates that are able to attract additional water.
COMPOUNDS
Compounds are substances composed of two or more elements chemically united in a definite proportion by weight. Water, Carbon dioxide and Sodium Chloride are examples of compounds. The metal is named first, and the ion second. FOUR TYPES OF INORGANIC COMPOUNDS TO UNDERSTAND CHEMISTRY - 1. ACIDS 2. BASES 3. SALTS 4. OXIDES
COVALENT BOND - HONC 1234
Covalent bonds are mostly formed by non-metals having4, 5, 6, or 7 valence electrons. These bonds are formed by the sharing of electrons between two atoms. Each bond is formed by the sharing of two electrons.
CRYSTALLIZATION - LIQUID
Crystallization -The process by which a substance is given definite form.
DIFFUSIBILITY - GASES
DIFFUSIBILITY refers to the movement of gas if introduced into a container. If we were to open a bottle of embalming fluid in one corner of the prep room, we would soon smell the formaldehyde (formaldehyde is a gas) throughout the entire prep room. The formaldehyde has diffused throughout the room. The actual definition of diffusion is the movement of molecules or other particles in solution from an area of greater concentration to an area of lesser concentration until uniform concentration is reached.
ELEMENTS
Elements are defined as substances which cannot be decomposed by further chemical means. Elements are the things that we find listed on the Periodic Table. Magnesium, Iron, and Copper are examples
HEAT
Energy is measure in the form of heat. The standard unit is the calorie (cal), defined as the quantity of heat necessary to raise the temperature of 1 gram of water 1o Celsius at 15o Celsius. At other temperatures, slightly different quantities of heat are required for this change. In metabolic processes, the calorie is often too small a unit, so a kilocalorie (kcal or Cal), equal to 1000 calories, is used.
COVALENT COMPOUNDS
Equal sharing of electrons are polar.
MIXTURES
Examples of mixtures are air, salt and water, and embalming fluid.
PURE SUBSTANCES
Examples of pure substances are hydrogen, oxygen, carbon, mercury, water, carbon dioxide and sodium chloride. PURE SUBSTANCES ARE CLASSIFIED AS ELEMENTS OR COMPOUNDS
FORMULA
FORMULAS - Compounds have been defined as two or more elements chemically combined in a definite proportion by weight. The two or more elements that comprise a compound are called "constituents" of that compound and usually involve a metallic portion and a non-metallic portion. Metallic elements generally have a positive oxidation number and are written first in the formula. Non-metallic elements generally have a negative oxidation number and are written last in the formula. FORMULAS represent the abbreviation for a compound (just as a symbol is an abbreviation for an element). The definition of a formula is a combination of symbols used to express the chemical composition of a substance.
WATER - IMPURITIES
First class of impurities in water, the soluble solids. 1. Insoluble solids 2. Bacteria 3. Gases
HEAT OF FUSION
For every substance there is a specific quantity of heat that is absorbed to convert one gram of the solid to one gram of the liquid at the substance's melting point. This amount of heat is called the Heat of Fusion.
SPECIFIC GRAVITY
For liquids and solids, this property is the ratio of the mass of the substance to the mass of an equal volume of water at the same temperature. The equation is: Specific gravity = mass of the solid or the liquid/mass of an equal volume of water Because specific gravity is a ratio of two masses, it has no units.
FREEZING - LIQUID
Freezing - A change of state of matter from a liquid to a solid.
ACTIVITY - RADIATION
Gives the nuclear transformation rate of a decaying atom.
WATER - HARDNESS
Hard water contains certain minerals in solution, which destroy the cleansing action of soap. The minerals include calcium, magnesium, and sometimes iron (II). HARDNESS - is divided into two classes. Temporary & Permanent Hardness.
HYDROLYSIS
Hydrolysis is a major chemical reaction of salts, in which the ions of a salt break apart water molecules into H+ and OH- ions. The constituents of water are then introduced into the products of the reaction, in a double replacement reaction. An example is the hydrolysis reaction of copper sulfate. Hydrolysis is the single most important factor in the initiation of decomposition. In human remains, proteins, carbohydrates, and fats are split into amino acids, monosaccharides, and fatty acids and glycerine by the addition of water and enzymes. It is important to realize that water chemically reacts with these substances rather than merely dissolving them.
HYDROLYSIS
Hydrolysis is a process by which water is split by other compounds. Hydrolysis is a double-replacement reaction.
HYPERTONIC
Hypertonic indicates a more concentrated solution. Hyperactive person has more energy than normal. Placing a red blood cell in a hypertonic solution causes it to shrink.
HYPOTONIC
Hypotonic indicates a less concentrated solution. For example, if we have two solutions separated by a semipermeable membrane. a red blood cell is placed in a hypotonic solution it will swell, and may burst.
IONIC BOND
IONIC BONDS - These types of bonds result from the complete transfer of electrons from one atom to another. When atoms gain or lose electrons, ions are formed. The electrostatic interaction between a positive ion and a negative ion is called an ionic bond.
IONS
IONS - Very often in chemical interactions atoms lose or gain electrons. As a result there is no longer a balance between the positive charge on the nucleus and the negative charge of the electrons. The charged particles that result are called ions. If an atom loses electrons, it becomes a positively charged ion, since the number of protons in the nucleus will be greater than the number of electrons surrounding the nucleus. A negative ion is formed if an atom gains electrons, because then the number of electrons will be greater than the positive charge on the nucleus. Ions can be divided into MONATOMIC and POLYATOMIC IONS.
MELTING POINT - SOLIDS
If heat is added to a solid at a temperature below the melting point, the solid will absorb the heat and increase in temperature until the melting point is reached. The process of breaking apart by heat is MELTING, and the temperature at which it occurs is the MELTING POINT. If heat is added to a solid at a temperature below the melting point, the solid will absorb the heat and increase in temperature until the melting point is reached. During the melting process the temperature of the matter does not change. After all of the solid is converted into the liquid state, any additional heat will increase the temperature of the liquid.
VOLUME
If one forms a cube with dimensions of 1 meter in length, 1 meter in width, and 1 meter in height a volume is formed. Because this would be too large for practical laboratory work, the decimeter is used to make a smaller volume, properly called a cubic decimeter. This volume is more commonly referred to as a liter. The milliliter (ml) is another important volume unit. There are 1000 ml in 1 liter. A cube having a length, width, and height each equal to 1 centimeter has a volume of 1 cubic centimeter. Because 1 milliliter of water will fill this cube at 4o Celsius, it is consistent to say that 1 milliliter equals 1 cubic centimeter.
SOLUTION - AQUEOUS
If the liquid is water, the solution is an AQUEOUS SOLUTION. An example of an aqueous solution is embalming fluid. Embalming fluid consists primarily of formaldehyde (gas), glycerol (liquid), and sodium chloride (solid) dissolved in water to form a homogenous mixture.
ATOMIC WEIGHT
If the number of protons and neutrons for any atom are added together, the atomic mass is approximately determined. This sum is generally referred to as the elements ATOMIC WEIGHT.
RADIOACTIVITY
If the proton-proton repulsions are not minimized within a nucleus, the nucleus decays to a more stable form. This spontaneous decay of nuclei is called radioactivity. Atomic number above 83 and some with lower atomic numbers are naturally radioactive.
LAW OF CONSERVATION OF MASS
In a chemical change, matter is neither created nor destroyed, merely changed from one form to another. In other words, the total amount of what is produced is equal to the total amount of starting material.
ALLOTROPIC
In addition to being a diatomic molecule, oxygen can exist in other forms. When an element exists in two or more different forms, each with its own physical and chemical properties, it is called ALLOTROPIC. There are three allotropes of oxygen: O3 O2 O Ozone Molecular Oxygen Nascent Oxygen (unstable) (stable) (unstable)
EXPANSIVITY - GASES
In contrast, a gas may increase its volume when heated. This demonstrates the concept of EXPANSIVITY. If we let our balloon float to the ceiling, and it comes in contact with a light, the balloon will burst. We have heated the gas until it gains enough energy to increase the volume of the balloon until it bursts.
CHEMISTRY - MAJOR DIVISIONS
Inorganic, organic and biochemistry are the major divisions.
ARTIFICIAL TRANSMUTATIONS
It is possible to cause a transmutation by bombarding nuclei of one element with other particles. Bombardment reactions are the basis of the process of nuclear fission, splitting a nucleus into smaller fragments.
LIQUIDS
LIQUIDS - If the pressure on a gas is increased or the temperature is lowered, interactions between particles occur. When theses interactions become strong enough to hold the particles together, the gas changes to the liquid state. The liquid state is intermediate in properties between the gaseous and solid states. Free space between the liquid particles is minimal, so liquids are practically incompressible. Liquids have a definite volume but will take on the shape of the bottom of their container.
DIFFUSION - LIQUID
Like gases, liquids will undergo DIFFUSION. However, they diffusemuch slower than liquids. This can be seen by adding a drop of ink to water. After a period of time the entire amount of water will take on the color of the ink because of diffusion.
AQUEOUS BASES
Like those of acids, the strengths of bases in aqueous solutions are determined by the percent dissociation of the compounds into positive ions and hydroxide ions. Sodium hydroxide and potassium hydroxide are strong bases and are caustic substances. They can cause severe burns to the skin. When used as 10% solutions they can be used to remove sloughed skin in burn cases in the prep room. Calcium hydroxide and magnesium hydroxide are also strong bases but they have low solubilities in water and are not caustic. They are classified as strong, since the small amount that does dissolve dissociates approximately 100%. Aqueous ammonia, is a weak base and is formed by dissolving ammonia gas, NH3, in water followed by ionization:
SURFACE TENSION
Liquids also exhibit a property called SURFACE TENSION. Surface tension is the force that acts on the surface of a liquid and tends to minimize surface area. A pin will actually float on the surface of a glass of water because of surface tension. Surface tension is a problem that exists when embalming. Manufacturers of embalming fluids add surfactants to their products to reduce the surface tension. Without them the fluid will not flow freely into the cells.. It is defined as a force that causes the surface of a liquid to contract. Molecules within the bulk of a liquid are attracted equally in all directions by neighboring molecules. The molecules at the surface of a liquid are attracted only downward or sideways. As a result the surface contracts.
MATTER
Matter is anything that occupies space and possesses mass.
MONATOMIC IONS
Monatomic ions are a charged entity consisting of only a single atom.
SOLUTION - PROPERTIES
NON-VOLATILE HIGH BOILING POINT FREEZES AT LOWER TEMPERATURE FILTER DIFFUSION OSMOSIS Nonvolatile (does not evaporate readily) substance as a solute, boils at a higher temperature and freezes at a lower temperature than does the pure solvent of the solution. A solution of sodium chloride and water has a higher boiling point than pure water. The boiling-point elevation is proportional to the concentration of the solute. Similarly, a solution shows a freezing-point depression in contrast to the freezing point of the pure solvent. Another physical property is stability of the solution when filtered. Since true solutions are homogeneous, the solute can not be removed by filtration. Similarly, the solute will not separate from the solution while standing. Another important physical property of solutions is diffusion. When the components of a solution are initially added to one another, regions of unequal concentration may result. To attain a uniform concentration throughout the solution, particles move from regions of higher concentrations to regions of lower concentrations. This is the definition of diffusion. The rate of diffusion is influenced by such factors as temperature, pressure, and molecular weight of the diffusing substance. High temperatures tend to increase the rate of diffusion. Lower molecular weight molecules will diffuse faster than high molecular weight molecules. Agitating the solution (stirring) will also increase the rate of diffusion. Osmosis is diffusion through membranes. Consider two aqueous solutions of different concentrations separated by a membrane through which only solvent particles can pass. Such a membrane is described as semipermeable. In order to equalize the concentrations on both sides of the membrane, there will be a net flow of water from the solution of lower solute concentration to the solution of higher solute concentration. The diffusion of the water is from a region of higher water concentration to one of lower water concentration. Water is diffusing from a dilute to a more concentrated solution. In reference to osmosis certain terms are used to compare concentrations. Two solutions of equal concentration are described as ISOTONIC. If two solutions are of different concentrations, HYPERTONIC AND HYPOTONIC are used. Hypertonic indicates a more concentrated solution. Hypotonic indicates a less concentrated solution. For example, if we have two solutions separated by a semipermeable membrane.
ACID ANHYDRIDES (NON-METALLIC OXIDES)
Nonmetallic oxides react with water to form acids. Nonmetallic oxides are called ACID ANHYDRIDES.
ACIDS-NUMBER OF ELEMENTS
Number of Elements - Acids that are composed of hydrogen and one other element are binary or hydro-acids. Acids that contain oxygen in addition to hydrogen and another nonmetallic element are ternary or oxy-acids. Binary acids derive their names from the element other than hydrogen. Their names always begin with the prefix hydro and end with the suffix -ic
SOLUBILITY
Oil and water do not mix. This is an expression of difference in solubility. Another familiar example of solubility is that it is possible to add salt to water and see it dissolve.
PLASTER OF PARIS
One example is calcium sulfate which in its partly anhydrous form is called plaster of Paris, and in its fully hydrated form is called gypsum.
OXIDATION NUMBERS
Oxidation numbers are positive and negative numbers that are assigned to atoms to show whether they bond to other atoms by gaining or losing electrons. Certain rules are followed in the assignment of these numbers. Atoms in ionic compounds that lose electrons have positive oxidation numbers corresponding to the charges they acquire in the formation of the ions. Atoms in ionic compounds that gain electrons have negative oxidation numbers. In the ionic compound sodium chloride, sodium's oxidation number is +1 (because it loses and electron) and chlorine's oxidation number is ?1 (because it gains an electron.
COMBUSTION
Oxide
POLYATOMIC IONS
Polyatomic ions are a group of atoms that act as a unit and possess a charge. An ion that is composed of more than one atom. (contained within the parenthesis)
PROTONS
Protons are positively charged particles with a mass approximately equal to the mass of one hydrogen atom. Protons are said to have a charge of +1. All atoms have at least one proton. The total positive charge on a nucleus is determined by the number of protons. The number of protons is equal to the atomic number. This number gives the atom its identity. All atoms with only one proton are hydrogen atoms. All atoms with six protons are carbon atoms. All atoms with eight protons are oxygen atoms.
pH
Pure water at room temperature contains equal concentrations of hydrogen and hydroxyl ions. Such water is described as neutral. If an acid is added to the water the H+ concentration increases and the solution is no longer neutral. Addition of a base to pure water also destroys neutrality by increasing the OH- concentration. The intensity of the acidity or basicity of a solution is commonly expressed by chemists in terms of pH. 1. The pH scale has a range from 0 to 14. 2. pH values less than 7 represent acidic solutions. The intensity of the acidity increases as pH values decrease. 3. pH values greater than 7 represent basic solutions. The intensity of the basicity increases as the pH values increase 4. A neutral solution has a pH of 7.
RATIO
RATIO - Some concentrations are expressed as the weight of solute to the weight of solution. A common concentration for the disinfectant HgCl2 is 1:1000.
SOLIDS
SOLIDS - In a solid the particles are held tightly to one another by some type of chemical bond. Because of the forces between particles, solids have a definite shape and volume. Solids are nearly incompressible and do not expand significantly with increasing temperature. The strong attractive forces between the particles prevent expansion. Likewise, repulsive forces between the negatively charged electrons associated with each particle prevent compressibility. The distance between the particles is a balance between the attractive and repulsive forces. Even though there is much order in solids, the particles are not motionless. They move back and forth, up and down, vibrating within limits of retaining the shape of the solid.
HEAT OF VAPORIZATION
Similarly, every substance has a Heat of Vaporization. This is defined as the amount of heat necessary to change one gram of a substance from liquid to gaseous state at the boiling point. The heat of vaporization of water is 540 calories per gram. Keep in mind that this occurs at water's boiling point of 212oF. Water has a very high heat of vaporization and heat of fusion. This is due to hydrogen bonding which we will discuss in a later chapter.
ELECTRONS
Since atoms are known to be neutral, the positive charge of the nucleus must be balanced by an equal negative charge, which is provided by the electrons. Each electron has a charge of -1. Since electrons and protons have the same magnitude of charge but one is negative and the other positive, a neutral atom has the same number of electrons and protons. Since we know that a Hydrogen atom has one proton, a neutral hydrogen atom must have one electron. Carbon has six protons; therefore, a neutral carbon must have six electrons. The interaction of the positively charged nucleus and the negatively charged electrons is the force that holds an atom together.
SOLIDIFICATION - LIQUID
Solidification- The conversion of a liquid or gas into a solid form.
ELECTROLYTES
Solutions that allow electrolysis are called ELECTROLYTES. Electrolysis depends on ions, so substances that dissociate to a large extent in a solution are good conductors of electricity and are called strong electrolytes. Weak acids and bases that dissociate slightly are weak electrolytes. Substances that do not form appreciable numbers of ions in solution are nonelectrolytes. Pure water and most organic compounds are nonelectrolytes.
SUBLIMATION
Some forms of matter undergo changes in state by which they pass directly from the solid state to the gaseous state. This is a physical change. i.e. dry ice(solid carbon dioxide) The vapor we see above the block of dry ice is carbon dioxide in the vapor form. The dry ice goes from the solid form to the gaseous form without going to the liquid form.
EFFLORESCENT
Some hydrates behave in an opposite manner and give up their water of crystallization to the surrounding air. These substances are called EFFLORESCENT. Sodium carbonate, Na2CO3.10H2O, is a good example of an efflorescent substance.
BUFFERS
Substance known as BUFFERS are present in the blood to protect against changes in pH. These substances interact with acidic and basic substances that enter the blood, converting them into compounds that the body can excrete.
SALTS
Substances called salts are the fourth of the major types of inorganic compounds. In pure form salts usually exist as crystalline solids at room temperature. Salts are ionic substance. Those that dissolve in water dissociate into positive and negative ions. Classification - Salts are classified as normal, acidic, or basic. A normal salt is one in which all the replaceable hydrogen of the corresponding acid has been replaced by a metal. Sodium chloride (NaCl) is a normal salt, formed by the neutralization of hydrochloric acid (HCl) by sodium hydroxide (NaOH). Normal salts do not contain hydrogen in the negative part of the ion. An acid salt is one in which only part of the replaceable hydrogen of the acid has been replaced by a metal. An example is sodium bicarbonate (NaHCO3). This compound is formed from a reaction between sodium and carbonic acid (H2CO3). Basic salts contain one or more replaceable hydroxyl ions. An example of a basic salt is basic lead nitrate (Pb(OH)NO3).
REACTANTS
Substances written to the left of the arrow
PRODUCTS
Substances written to the right of the arrow
LEWIS THEORY
The Lewis Theory is more general than the Bronsted-Lowry or Arrhenius Theory. According to Lewis, an acid is any substance that accepts a pair of electrons and a base is any substance that donates a pair of electrons. For example: The o's represent the electrons in the outer shell of hydrogens. The x's represent the electrons in the outer shell of the oxygen and the chlorine. The water molecule donated a pair of its electrons to the HCl therefore, water is the base. A covalent bond forms between the hydrogen ion and water molecule, yielding the hydronium ion. Both electrons in the bond were originally with the oxygen. This is different from most covalent bonds in which one electron comes from each of the atoms joined in the bond. To distinguish these two types of covalent bonds, those in which both bonding electrons come from the same atom are called COORDINATE COVALENT BONDS. The Lewis Theory also includes metallic oxides and non-metallic oxides as acids and bases. According to the theory, metallic oxides have basic properties and non-metallic oxides have acidic properties. For example, BeO would have basic properties. It would donate a pair of electrons. NO2 would have acidic properties. It would accept a pair of electrons.
QUALITATIVE TERMS
The concentration of a solution may be expressed qualitatively or quantitatively. Two qualitative terms are dilute and concentrated. A DILUTE solution contains a relatively small amount of solute, while a CONCENTRATED solution contains a relatively large amount of solute. Other qualitative terms we should be familiar with are unsaturated, saturated, and supersaturated. A SATURATED solution contains all the solute the solvent is able to hold at a certain temperature and pressure. A solution that has not reached saturation is UNSATURATED. A SUPERSATURATED solution contains more of the solute than the solvent is normally able to hold. Supersaturated solutions are difficult to prepare and to maintain. The slightest bump to the container can bring the solute out of solution. The terms dilute and unsaturated are not the same. For example, a saturated solution of sodium chloride contains 36 grams in 100 grams of water. If a solution contains 30 grams of NaCl/100 grams of water, it is unsaturated and concentrated. If it contains 5 grams of NaCl/100 grams of water, it is unsaturated and dilute.
HALF-LIFE
The half-life of a particular radioactive atom is the amount of time that it takes for half of the initial amount of radioactive material to decay.
ATOMIC MASS
The mass of an electron is 1/1837 of the mass of a hydrogen atom. Since this is much less than the mass of a proton or neutron, an atom?s total mass is mainly due to the protons and neutrons. Protons and neutrons are defined as having a mass of one unit. If the number of protons and neutrons for any atom are added together, the atomic mass is approximately determined. This sum is generally referred to as the elements ATOMIC WEIGHT.
NAMING COMPOUNDS
The metal is named first, and the ion second. When a metal element is combined with one other nonmetallic element. In these cases, the name of the metallic element remains intact, but the nonmetallic element acquires an "-ide" suffix.
HYDROGEN
The most abundant element in the universe. Hydrogen is a homonuclear diatomic molecule. It has an atomic number of one, an atomic weight of one, and usually has an oxidation number of +1 except when combined with itself. PHYSICAL PROPERTIES 1. Hydrogen is a colorless, odorless, and tasteless gas. 2. Hydrogen is lighter than air. It is the lightest gas known. 3. Hydrogen is slightly soluble in water. CHEMICAL PROPERTIES 1. Hydrogen burns wit a hot, blue flame, forming water. 2. Hydrogen does not support combustion. 3. Hydrogen acts as a reducing agent. The second chemical property of hydrogen is that it does not support combustion. This means that pure hydrogen will extinguish a full flame. However, hydrogen can not be used in fire extinguishers because it so light that it is very hard to control. The third property of hydrogen is that it acts as a reducing agent.
TERNARY ACIDS
The names of ternary acids are derived from the element other than hydrogen and oxygen and end with the suffix -ic.
CHEMICAL BOND
The net attractive interaction between two atoms in a molecule is called a chemical bond.
ELECTROLYSIS
The presence of ions in a solution enables it to conduct electricity. The passage of an electric current through a solution is called ELECTROLYSIS.
DEHYDRATION
The process of removing the water of crystallization from a compound is.
ATOMS
The smallest particle of an element. The major parts of the atom are its nucleus and its electrons.
LENGTH
The standard unit of length is the meter. Other important length units are the decimeter(dm), centimeter (cm), millimeter (mm), and kilometer(km).
MASS
The standard unit of mass is the kilogram (kg). Mass measurements are most frequently made in the laboratory in units of grams (g). To relate mass to volume, 1 gram of pure water occupies a volume of 1 milliliter at 4ocelsius. Therefore, the density of pure water is 1.00 gram per milliliter at this temperature. Densities are always calculated by dividing the mass of a substance by the volume occupied by that mass.
ANHYDRIDES
The word anhydride means "without water". Oxides of metals and nonmetals are called anhydrides. By reacting with water they from either acids or bases. Typical anhydrides are CO2, SO2, Na2O, CaO and Fe2O3. The first two are oxides of nonmetals.
BIVALENT METALS
These metals have two possible oxidation states. When naming compounds containing these metals, we must indicate which oxidation state the metal is in.
RADIONUCLIDE
This is a general term used to describe any radioactive material.
IONIZATION
This property is defined as the dissociating of a substance into charged species that may be atoms or groups of atoms.
ACIDS
This table illustrates several methods of classification of acids. The usual ways acids are classified are by: • Number of hydrogens • Number of elements • Strength
BRONSTED-LOWRY THEORY
This theory extends the definitions of acids and bases to include as bases substances other than metallic hydroxides. According to the theory, and acid is a proton donor and a base is a proton acceptor. When hydrogen chloride dissolves in water, a proton is donated by hydrogen chloride to water: Hydrogen chloride donates the proton (H+) so it is the acid. Water accepts the proton so it is the base. In the reaction between ammonia and water, ammonia accepts a proton from water: In this case ammonia is the base because it accepts the proton and water is the base because it donates the proton. Ammonia (NH3) and the ammonium ion (NH4+) differ only by a proton. When the only difference between two substances is a proton, they are called a CONJUGATE ACID-BASE PAIR. The conjugate base of an acid is always determined by removing one proton from the acid. The conjugate acid of a base is the base plus a proton
GASES
Three important properties of gases are compressibility, expansivity, and diffusibility. COMPRESSIBILITY means that increasing the pressure on a gas may decrease the volume of a gas. You can decrease the size of a balloon by compressing it and the gas inside of it. In contrast, a gas may increase its volume when heated. This demonstrates the concept of EXPANSIVITY. If we let our balloon float to the ceiling, and it comes in contact with a light, the balloon will burst. We have heated the gas until it gains enough energy to increase the volume of the balloon until it bursts. DIFFUSIBILITY refers to the movement of gas if introduced into a container. If we were to open a bottle of embalming fluid in one corner of the prep room, we would soon smell the formaldehyde (formaldehyde is a gas) throughout the entire prep room. The formaldehyde has diffused throughout the room. The actual definition of diffusion is the movement of molecules or other particles in solution from an area of greater concentration to an area of lesser concentration until uniform concentration is reached. Gases are characterized as having no fixed shape and volume. That is to say that they will take on the shape and the volume of their container. Gases are also said to have the most Entropy of the three states of matter. Entropy is the measure of the amount of disorder or randomness. Solids are said to have the least amount of entropy. They are the most ordered.
MATTER - NATURE OF...
Three things define the nature of matter. Composition of a particular kind of matter, the forces holding its parts together, and its observable properties.
COORDINATE COVALENT
To distinguish these two types of covalent bonds, those in which both bonding electrons come from the same atom are called COORDINATE COVALENT BONDS.
SOLUTION
True solutions are homogeneous mixtures of two or more substances. Components of a solution can be elements or compounds, as well as gases, liquids, or solids.
ISOTONIC
Two solutions of equal concentration are described as ISOTONIC. If a blood cell is placed in an isotonic solution, it will neither swell nor burst.
PERIODIC TABLE -
VERTICAL COLUMNS ARE CALLED GROUPS OR FAMILIES. Within each of these families the elements have the same number of valence electrons. i.e. the elements in family IA have one valence electron. HORIZONTAL ROWS ARE CALLED PERIODS.. The horizontal rows on the table are called Periods. Each element in a row has one more proton and one more electron than the element before it. The physical properties of the elements change from metal to non-metal within a row from left to right. The elements to the left of the heavy line in each row are metals and those to the right are non-metals. In chemical reactions metals have a tendency to gain electrons and become negative ions.
WATER
Water is the most abundant compound. The human body consists of about 70% water. PHYSICAL PROPERTIES OF WATER 1. Water is a colorless, odorless, tasteless liquid. 2. It freezes at 00C and boils at l000C at standard atmospheric pressure. 3. Water has a heat of fusion of 80 calories/gram. 4. Water has a specific heat of 1 calorie/gram/0C. 5. It is a very good solvent for many substances. It is known as the "Universal solvent". It is also the primary vehicle for embalming fluids. CHEMICAL PROPERTIES OF WATER 1. Water is a very stable substance. It is thermally stable. If heated to temperatures near 20000C decomposition is minimal. 2. Water chemically reacts with active metals to liberate hydrogen. These active metals are listed in the electrochemical series. 3. It reacts with some metallic oxides to form bases: 4. Reacts with some nonmetallic oxides to form acids: 5. Water will form HYDRATES - a compound in which there is a chemical union between water and certain substances when they crystallize. Plaster of Paris is an example of a hydrate: 6. Water will enter into hydrolysis reactions. 7. Water is a key factor in both the decomposition of the human body after death, andthe attempt to control that process - the embalming process.
CRENATION
Water moves from a dilute solution to a more concentrated one, or out of the blood cell. This is shrinking of the cell is called CRENATION. It is the result of the net flow of water from inside the cell to the outside.
HEMOLYSIS
Water once again moves from a dilute solution to a more concentrated one. However, this time the movement of water happens to be into the blood cell. This is called HEMOLYSIS. It results from a net flow of water from outside the cell to the inside.
HYDROLYSIS
We can also write a double-replacement reaction called a HYDROLYSIS reaction. The definition of hydrolysis is a chemical reaction in which a substance is broken down or dissociated by water; a reaction between a salt and water to yield an acid and a base of unequal strengths. An example is the reaction of copper (II) sulfate with water. CuSO4 + 2HOH Cu(OH)2 + H2SO4 Salt Water Weak base Strong acid
LAW OF CONSERVATION OF MATTER
We cannot have one atom of aluminum on the left and two on the right.
OXYGEN
a nonmetallic element of great importance because it is the most abundant element on earth. It comprises 21% of the volume of atmospheric air and 89% of the weight of water. PHYSICAL PROPERTIES 1. Oxygen is a colorless, odorless, and tasteless gas. 2. Oxygen is heavier than air. 3. It is slightly soluble in water 4. It can be liquefied and solidified by extreme pressure and low temperature. CHEMICAL PROPERTIES 1. Reacts with many substances slowly at ordinary temperatures but rapidly at high temperatures. 2. Reacts with many metallic and nonmetallic elements to form oxides. 3. Supports combustion. This does not mean that oxygen burns. It means that oxygen helps other things burn. In fact, it is helpful to define burning as the process of chemically adding oxygen to another substance with the production of an oxide. Another word for burning is COMBUSTION. 4. Oxygen acts as an oxidizing agent.
ISOTOPES
are atoms of the same atomic number but with different masses.
DENSITY
as mass per unit volume(D=M/V). expresses the relationship between its mass and the volume occupied by that mass.
CHANGES - PHYSICAL
as one that does not cause a change in the chemical composition of a material. Common physical changes are the meting of ice and the boiling of water.
SOLUTION - GASEOUS
at least one gas is dissolved in another. When gases are placed into a container, they mix in all proportions. Any mixture of gases is homogeneous and meets the requirements of a true solution.
DIATOMIC MOLECULE
being shared. In all homonuclear diatomic molecules, (two atoms of the same element bonded together) the electrons in the bond are shared equally by the bonding atoms. Since the atoms are of the same element, neither nucleus has a tendency to attract the electrons more than the other.
DECOMPOSITION - ACIDS
decomposition into water and the corresponding oxide, because of its instability.
NUCLEUS
described as small, because its diameter is about 1/10,000 of the diameter of the entire atom. Although the nucleus is very small most of the mass of the atom is contained in the nucleus. The nucleus has a positive charge. The nucleus contains several types of particles. We will be concerned with the PROTON and the NEUTRON.
EXOTHERMIC
describes and process that liberates heat. Gas = Liquid + Heat Liquid= Solid + Heat
ENDOTHERMIC
describes any process that absorbs heat. Solid + Heat = Liquid Liquid + Heat = Gas Setting of Plaster of Paris Plaster of Paris + Water = Gypsum + Heat Plaster of Paris reacted with water to form a hard crystalline substance called gypsum. In the transition from a higher energy state (liquid) to a lower energy state (solid), energy in the form of heat must be released.
DISSOCIATION - ACIDS
dissociation into a hydrogen ion and a negative ion, which shows its acidic properties:
DOUBLE BOND
four electrons between the two oxygens to be shared. Oxygen forms what is called a double bond.
MASS
indicates the quantity of matter present in an object. Mass will not change with distance from the center of gravity.
CHEMICAL PROPERTY
is a characteristic that can be observed when the substance is interacting with other forms of matter. The interaction results in alteration of the chemical composition of the substance. For example, a chemical property is shown when a substance burns. Another example of a chemical property is the interaction of certain substances with water. When sodium is added to water, two new substances, hydrogen gas and sodium hydroxide, are formed. Not all substances simply dissolve in water. Some will actually chemically react with it. A third chemical property is the effect on matter of substances known as acids and bases.
PHYSICAL PROPERTY
is a characteristic that can be observed without altering the chemical composition of a substance. Typical ones are color, odor, and taste. Another common physical property is the state in which a type of matter exists at a given temperature and pressure.
HYDRATES
is a compound in which there is a chemical union between water and the molecules of certain substances. The physical appearance of a hydrate is crystalline.
ANION
is a negatively charged atom or group of atoms.
CATION
is a positively charged atom or group of atoms
PHYSICAL CHANGE
is a process that manifests a physical property. Common physical changes are changes in state. For example, when ice melts, three physical properties - water's characteristics as a solid and as a liquid and its melting point - are demonstrated. The chemical composition of the water has not been altered
OXIDE
is a substance containing only two elements, one of which is oxygen. Oxides are formed during cremation. Whenever matter is burned in the presence of oxygen, oxides are formed. Another name for this process is combustion.
EQUATION
is an abbreviation for a chemical change.
SOLUTION - SOLID (ALLOY)
is defined as a metallic substance that is composed of two or more metallic elements. In these solids the components are randomly dispersed throughout each other. Examples of alloys are: ALLOY COMPONENTS Brass Copper and Zinc Bronze Copper, tin and sometimes zinc Stainless steel Iron, chromium and nickel Sterling silver Copper and silver Both stainless steel and bronze are used in casket construction.
ENERGY - KINETIC
is energy of motion. If we put that battery in a toy car and turn it on, the motion of the car is considered kinetic energy.
ENERGY - POTENTIAL
is energy that is inherent in a system before an act or process occurs. A battery that is not being used has potential energy. That is to say that it has the potential to make something work. I.E. The chemical energy that chemical substances store is considered a form of potential energy. One example of chemical potential energy is that which is stored in food and released by metabolic reactions for maintenance of bodily functions.
CHEMICAL CHANGE
is one that manifests a chemical property. Chemical changes are rusting of iron, burning of paper, cremation and decomposition of human remains. Each of these processes represents an interaction between a substance and other forms of matter, causing alteration of the chemical composition of the original material.
MELTING POINT
is that temperature at a given pressure at which a substance changes from the solid state to the liquid state. The freezing point of a substance is the same as its melting point, because the process of freezing is the opposite of melting. A substance undergoes the transition from the solid to liquid state at its melting point. For every substance there is a specific quantity of heat that is absorbed to convert one gram of the solid to one gram of the liquid at the substance's melting point. This amount of heat is called the Heat of Fusion. It takes 80 calories to convert one gram of ice to one gram of liquid water at 32o F (water's melting point). The heat of fusion of water is 80 calories per gram.
CHEMISTRY
is the study of the nature of matter and the changes that matter undergoes.
ENTROPY - GASES
matter. Entropy is the measure of the amount of disorder or randomness. Solids are said to have the least amount of entropy. They are the most ordered.
WEIGHT
of an object is the measure of the gravitational force exerted on it by Earth. Weight will change as distance from the center of gravity changes.
SOLUTION - LIQUID
one in which a gas, liquid, or solid is dissolved in a liquid. Dissolving of salt in water, and of iodine in alcohol are liquid solutions. The latter is referred to as a tincture.
POSITRON
positively charged beta particle which is called a positron. BETA RADIATION
CHEMISTRY - INORGANIC
refers to nonliving substances, so it is the study of minerals and other inanimate materials commonly found in the Earth. Unfortunately, certain compounds such as carbon monoxide, carbon dioxide, the carbonates and the bicarbonates are included in the study of inorganic compounds.
SUBSCRIPTS
represent the definite proportion by weight BETA - subscripts refer to charges.
SUPERSCRIPTS
represents oxidation numbers - BETA - superscripts refer to mass numbers
COMMON STATES OF MATTER
solid, liquid, and gas. The state of matter is determined by the amount of energy is possesses. The gaseous state is the most energetic, the liquid state is of intermediate energy, and the solid state has the least energy. The degree of energy of a state is reflected by the type of motion possessed by the particles. For example, in a solid the particles vibrate around fixed positions, in liquids the particles slide past one another, and in a gas each particle possesses random, rapid motion independent of the other particles. Since heat is a form of energy, the change from solid to liquid to gas by a particular form of matter is accomplished by absorption of heat. If the reverse occurs, that is to say, as we go from a gas to a liquid to a solid, energy is liberated. A familiar example of these concepts is the action of a refrigerator. In the formation of ice cubes, a freezer removes heat from liquid water so it can solidify. When ice is left out on a hot day, it absorbs energy in the form of heat from the surroundings and will melt.
VALENCE ELECTRONS
specific atom the electrons in the outermost shell are called valence electrons. They determine the chemical properties of the atom. The number of valence electrons in an atom is also important, because, with few exceptions, most atoms with the same number of valence electrons have similar chemical and physical properties.
BOILING POINT
that temperature at which a substance changes from the liquid state to the gaseous state.
ENERGY
the ability to do work. Kinetic Energy & Potential Energy
CHEMISTRY - ORGANIC
the study of certain carbon containing compounds.
CHEMISTRY - BIOCHEMISTRY
the study of compounds produced by living organisms. Embalming chemistry is the study of those types of matter and changes in matter related to the disinfection and preservation of human remains.
SOLUBILITY
there is a limit to the amount of solute which can be dissolved in a given quantity of solvent. That limit is the solid solute's SOLUBILITY in a liquid solvent. 1. Polar & Non-Polar 2. Temperature 3. Pressure POLAR/NON-POLAR Water and salts are alike in that they are polar molecules. Iodine in contrast is a nonpolar molecule. In a polar molecule there are regions of positive and negative charges. All ionic compounds are polar, and those covalent compounds in which there is unequal sharing of electrons are polar. Since sodium chloride is ionic and water is polar covalent, salt dissolves in water. Nonpolar molecules are formed by covalent bonding with equal sharing of electrons in the bonds. All homonuclear diatomics and most organic compounds are nonpolar. Since iodine (I2) is nonpolar, it will not dissolve in polar water molecules. Likewise, oil, which is an organic nonpolar molecule, will not dissolve in water. TEMPERATURE The solubility of gases in liquids is decreased by an increase in temperature. Another consequence of temperature's influence on solubility is that the procedure of hot water embalming is less efficient than room temperature embalming. Recall that an exothermic process is one in which heat is liberated and an endothermic process is one in which heat is absorbed. An equation for an exothermic dissolving process can be written as follows: SOLUTE +SOLVENT SOLUTION +HEAT The addition of heat shifts the reaction in the backward direction, decreasing the solubility. Therefore, in an exothermic dissolving process solubility is increased by lowering the temperature. An equation for an endothermic dissolving process can be written as follows: SOLUTE+SOLVENT+HEAT SOLUTION PRESSURE Its influence is limited to gases. The solubility of all gases is increased as the partial pressure of the gas above the solution is increased. When a can of soda is opened, the pressure decreases, causing the carbon dioxide solubility to decrease. Consequently bubbles of gas escape.
CHANGES - CHEMICAL
those that result in the formation of a new substance. Chemical changes are those that result in the formation of new substances. An example of a chemical change is the decomposition of liquid water into hydrogen gas and oxygen gas when an electric current passes through it. Decomposition of human remains and the embalming process are considered chemical changes.
POLAR COVALENT BOND
two unlike atoms bond. One atom will have a greater affinity for the electron and become partially negative, thus leaving the other atom partially positive. The electrons are shared but not equally.
ELECTRONEGATIVITY
we find that some attract electrons more than others. A measure of the attractiveness of an atom for electrons is called Electronegativity.
NEUTRALIZATION
This is a NEUTRALIZATION reaction. The definition of a neutralization is the reaction of an acid and a base to produce salt and water.
DOUBLE-REPLACEMENT (METATHESIS) REACTION -third chemical reaction change
Two significant examples are neutralization and hydrolysis. Both of these are integral to the understanding of what is to be accomplished during embalming. Double-replacement reactions are identified by the presence of two reactants and two products. The Products are obtained by changing partners of the plus and minus parts of the reactants. i.e. HCI + NaOH __________H2O + NaCl
EXPOSURE - RADIATION
1. EXPOSURE: evaluates the ability of gamma rays to produce ions in air. It is defined as the amount of ionization or charge produced per unit mass of air by gamma rays.
GEIGER-MUELLER COUNTER RADIATION DETECTORS - SURVEY METER
1. Geiger-Mueller counter: Able to measure alpha, beta and gamma radiation.
RADIATION PROTECTION
1. TIME: Minimizing the amount of time one is in contact with a radioactive material is a protective measure against radiation. 2. DISTANCE: Measurement of the intensities of radiations at various distances from a source shows that the intensity decreases with the square of the distance from the source. We can express this mathematically as: This means that if we are at a distance of 2 meters from a source of radiation, the intensity is one-fourth of what it is at the source itself. 3. SHIELDING: A very effective protection against radiation. Radionuclides are usually stored in lead containers for this purpose.
ABSORBED DOSE - RADIATION
2. ABSORBED DOSE: The amount of energy absorbed by a unit mass of matter.
SCINTILLATION COUNTER - RADIATION DETECTORS - SURVEY METER
2. Scintillation counter: Also able to measure alpha, beta and gamma radiation.
DOSE EQUIVALENT - RADIATION
3. DOSE EQUIVALENT: Used to compare the biological effects of the different forms of radiation
COEFFICIENT
3. The numbers in front of the formulas are called coefficients.
ALPHA DECAY
ALPHA DECAY: As the result of alpha decay, the mass number of the reactant (decaying atom) is decreased by 4 and the atomic number is decreased by 2. The identity of the product atom is determined by the new atomic number. For example: Uranium has gone through alpha decay to become thorium with a new atomic number of 90.
ALPHA RADIATION
ALPHA: This form of radiation consists of particles that each contain two protons and two neutrons. Because their atomic number is 2, they are equivalent to nuclei of helium. Each particle has double positive charge. The velocity of these particles is approximately one-tenth the speed of light. Because of their mass and charge, alpha particles travel only a few centimeters in air. It is possible to stop them by a piece of paper. Since they can penetrate body tissue only about 0.05 millimeter, they cannot reach internal organs from outside the body. If ingested or inhaled, alpha particles will damage cells of internal organs. This damage is caused by the high ionizing power of alpha particles. Their +2 charge causes them to remove electrons from the outer energy levels of other atoms.
POLYPROTIC
Acids that dissociate into more than one hydrogen are POLYPROTIC. These are more specifically described as diprotic and triprotic. Sulfuric acid, H2SO4is diprotic and phosphoric acid, H3PO4, is triprotic.
BETA DECAY
BETA DECAY: The thorium-234 produced by the alpha decay process previously described is also radioactive. It decays by emission of a negative beta particle and a gamma ray: Because the mass of an electron is so much less than that of a proton, it is given a mass number of zero. The atomic number of -1 is assigned to an electron. The alpha decay or uranium-238 begins a series of decays called a radioactive disintegration series. The series ends with the formation of lead-296, a stable atom. Each of the decaying atoms in the series is referred to as a RADIONUCLIDE. This is a general term used to describe any radioactive material.
BETA RADIATION
BETA: Consists of very small particles that have a mass of 1/1837 that of a proton. There are two types of Beta radiation. The more familiar type of beta particle has a charge of -1 and is an electron. The less familiar particle is the positively charged beta particle which is called a positron. Electrons are formed within a nucleus by the breakdown of a neutron into a proton and an electron. The proton remains in the nucleus; the electron is emitted. If, in contrast, a proton is broken down to a neutron within a nucleus, a positive beta particle, the positron, is emitted from the nucleus.
TRANSMUTATION
Both alpha decay and beta decay lead to the conversion of an atom of one element into an atom of another. This type of nuclear change is called TRANSMUTATION.
DIALYSIS
Colloidal particles can be separated from true solution particles by the process of DIALYSIS. Certain natural membranes such as found in animal kidney tubules allow small ions and molecules, but not larger colloidal particles, to diffuse through them. This selective diffusion is called dialysis.
DECOMPOSITION - second chemical change
Decomposition is the opposite of synthesis and is defined as the breakdown of a compound into its constituent parts. It is an extremely important reaction, since it is the process which embalming attempts to retard. Just as a synthesis reaction may be identified by the presence of two reactants and one product, decomposition is identified by the presence of one reactant and two products.
DOSIMETERS - RADIATION
Dosimeters: measure individual exposures to radiation. 1. Film badges: Photographic film is darkened on exposure to radiation. 2. Pocket dosimeters: used for the detection of gamma rays. 3. TLDs: Chemical compounds release light proportional to the radiation dose when processed
GAMMA RAYS
GAMMA RAYS: The most penetrating type of radiation from a radioactive atom is gamma radiation. It is a type of electromagnetic radiation like visible light and x-rays. Gamma rays travel as waves, but they are generally higher in energy. Frequently, gamma rays are emitted from a nucleus during the process of either alpha or beta decay. In air, gamma rays can travel many meters. Lead is necessary to stop them. Gamma rays penetrate the human body and can damage both the cells and the tissues of internal organs. The ionizing ability of this form of radiation is less than that of alpha or beta particles.
MONOPROTIC
Number of Hydrogens - Those acids that yield one hydrogen per molecule in solution are called MONOPROTIC.
OCCUPATIONAL EXPOSURE
OCCUPATIONAL EXPOSURE: MOST COMMON - The first source is the less likely to pose a problem to the embalmer for two reasons. First there have been only 112 fatal radiation accidents in the world over a period of 53 years. Second, a body that has been contaminated with dangerously high levels of radiation will not be released to the embalmer until radiation levels have been reduced to an acceptable level by standard decontamination procedures. By the time the embalmer receives one of theses remains, the only problems that should be encountered will be those associated with delayed embalming and refrigerated or frozen bodies.
OZONE
Ozone is prepared by passing a high-voltage electrical discharge through oxygen. The physical properties of ozone are: 1. Pale blue-colored gas. 2. Penetrating odor. The clean smell that you notice after an electrical storm is caused by ozone. The chemical properties of ozone are: 1. More active chemically than oxygen, but less stable. 2. Readily decomposes, liberating nascent (newly formed) oxygen. 3. Has great bleaching and deodorizing abilities. This is due to its high oxidizing capabilities. Has been used to treat drinking and waste water. It is a true deodorant because it destroys the odor instead of just masking it.
PERMANENT HARDNESS
PERMANENT HARDNESS - This type of hardness can not be removed by boiling. Other methods such as the addition of chemicals must be used. Permanent hardness is caused by the chloride and sulfate salts of calcium and magnesium. 1. Removal of hardness by adding sodium carbonate (washing soda). The chemical reaction is: The double-replacement reaction, which occurs, converts the soluble calcium chloride into the insoluble calcium carbonate. 2. Use of soap to remove hardness Hard water, by definition, destroys the cleansing action of soap. This happens because soap chemically reacts with the hard water minerals to form a deposit called curd. Since the formation of curd effectively removes the minerals from the water, the use of soap qualifies as a method for softening water. The main drawback of this method is its lack of economy. A certain portion of the soap is used by the dissolved minerals before the remainder of the soap is able to function as a cleansing agent. 3. Use of ion-exchange systems Manufacturers of water-softening devices usually include in their advertising some statement regarding the savings on soap that consumers will experience. We have already discussed that hard water uses a certain proportion of soap. Softened water does not use as much soap, so more is available to do what it was intended to do, clean. Most commercial water softeners contain some kind of an ion-exchange system, in which hard-water ions such as calcium are exchanged for soft-water ions such as sodium. In many instances ions are exchanged in a medium called a resin. This resin is composed of thousands of plastic beads, which are charged with sodium ions. When hard water passes over the resin, calcium ions displace the sodium ions and stick to the resin. The sodium ions are released from the resin and pass into the solution. An ion-exchange system simply "swaps" one type of ion for another type. 4. Distillation This process consists of the vaporization and condensation of water. All the substances that cause hardness in water are soluble. When water is vaporized, these substances remain in the distillation vessel or container.
RADIATION - PREP OF AUTOPSIED BODY
PREPARATION OF THE AUTPOSIED BODY: Radiation encountered from nonautopsied bodies is in the form of gamma rays, which have the highest penetrating power of the three types previously described. Radiation exposure from autopsied remains involves beta particles in addition to gamma rays. Once any implants placed in the body have been removed, the body no longer contains radioactivity. Implants should never be touched directly with the hands.
RADIONUCLIDE THERAPY
RADIONUCLIDE THERAPY: MOST COMMON - High levels of radiation can occur during treatment of malignant diseases. Patients receiving large doses of radionuclides are usually required to remain hospitalized until their content of radioactivity is less than 30 mCi. This requirement, which is called the 30 mCi rule, may not be the best criterion for release of a patient. A better criterion is that patients remain hospitalized until their content of radiation is low enough to cause a dose no greater than 0.1 rem to individuals with which they make contact Radionuclides are not given to moribund patients. Consequently, deceased patients with large amounts of radionuclides will be encountered only rarely. Hospital personnel are required by the conditions of a license for the use of these substances to monitor and certify to the embalmer the radioactive condition of the patient.
REDUCTION AGENT - GER (Gain of electrons is reduction)
Reduction is: 1. The removal of oxygen from a substance. 2. The addition of hydrogen to a substance. 3. The addition of electrons to a substance. 4. The decrease in the oxidation number of a substance. I.E. In this reaction, methyl alcohol is oxidized, because it loses hydrogen. Oxygen undergoes reduction because it gains the hydrogen. Methyl alcohol is the reducing agent, and oxygen is the oxidizing agent. The loss of hydrogen by reducing agents occurs in many biological oxidation-reduction reactions. As our bodies break down ingested foods, these molecules frequently lose hydrogen ions and electrons, which in turn are accepted by very large molecules that act as oxidizing agents.
COLLOIDS
Some examples of colloids are protoplasm, blood plasma, soap solution, mayonnaise and smoke. A notable quality of colloids is Brownian movement. Particles in colloids move randomly, owing to their bombardment by solvent molecules. Colloids have an intermediate particle size.
SUSPENSIONS
Suspensions are mixtures such as milk of magnesia, and clay and water. The major distinguishing factor of true solutions, colloidal solutions, and suspensions is particle size. Suspensions have the largest particle size. True solutions have the smallest particle size and colloids have an intermediate particle size.
TEMPORARY HARDNESS
TEMPORARY HARDNESS - Can be removed by boiling and is due to the presence of the bicarbonate salts of calcium and magnesium. Boiling water containing these salts produces a decomposition reaction converting these soluble substances into insoluble substances. The white crystal deposit found around bathtub and sink faucets is evidence of this reaction. When very hot water is run through these outlets, the heat decomposes the bicarbonates dissolved in the water. As a result, the insoluble carbonates are deposited on the fixtures.
REACTION RATE - FACTORS
Temperature - There is a direct proportion between temperature and the speed of a chemical reaction. An increase in temperature increases the speed of reactions, and a decrease in temperature decreases the speed of reactions. Physical State - This refers to the size of the particles of the reacting substances. The smaller the size of our reactant, the more surface area we have on which the reaction can occur. We can dissolve much more finely ground sugar in a glass of iced tea than course ground sugar. Notice this is a physical change and not a chemical change. Concentration - The rate of a chemical reaction is proportional to the molecular concentration of the reacting substances. The greater the concentration, the faster the reaction. The lesser the concentration, the slower the reaction. Light - Many chemical reactions are caused or accelerated by light. These are called photochemical reactions. Embalmed jaundiced remains may turn green when exposed to fluorescent lights. Fluorescent lights are missing one component that ordinary visible light has. This condition may be avoided by the use of "color-corrected" fluorescent lights that do not lack this component of light. These lights may actually cause a photochemical reaction that results in a pink tone to the skin. Pressure - Pressure has very little effect on chemical reactions other than those involving gases. Reactions between gaseous reactants are accelerated by an increase in pressure and slowed by a decrease in pressure.
RADIONUCLIDE THERAPY - VEHICLES OF
VEHICLES OF RADIONUCLIDE THERAPY: Common methods by which radionuclides are introduced into a body are by ingestion, injection, and implantation. Radioactive colloids may be injected directly into localized malignant growths. Implants are usually in the form of radioactive needles, seeds, wires, and pellets. Ingested and injected radionuclides are generally disseminated throughout body fluids, organs, and their protective serous membranes. Implanted materials usually remain in one place, unless the accidental rupture of seeds, pellets, or needles causes generalized dissemination. The danger to the embalmer from any of the ante mortem treatments is influenced by whether or not an autopsy has been performed.
SYNTHESIS - first chemical change
Writing Equations - When we wrote the formulas for all of the previous compounds, we expressed the end result of a chemical change called SYNTHESIS. For example combine copper with oxygen to form copper (II) oxide. Cu0 + O20 Cu+2O-2 This is a synthesis reaction. One way to identify synthesis reaction is that there are two reactants, but only one product. i.e K+ I _______KI
OXIDIZING AGENT - LEO (Loss of electrons is oxidation)
a substance, that substance undergoes oxidation. Since oxygen has caused this process, it is called an oxidizing agent. When the oxidizing agent has performed its task, it is reduced. Reduction is the counterpart of oxidation and always accompanies it.
