chemistry lab final

Each element has a unique emission spectrum; thus, an emission spectrum can be used to identify elements. In 1885 Johannes Balmer discovered a relatively simple formula relating the wavelengths present in the visible portion of the emission spectrum of hydrogen to a series of integers Rydberg equation

1/A=Rh(1/2^2-1/n^2) In this formula, λ is the wavelength of light, RH is the Rydberg constant, and n is an integer. Each of the four wavelengths in the visible portion of hydrogen's emission spectrum is associated with one of the integers 3, 4, 5, or 6. Hydrogen also emits light outside the range of visible wavelengths (e.g., in the ultraviolet). These additional lines can be incorporated into a generalized version of Balmer's equation, known as the Rydberg equation: see notes In this equation, ni and nf are integers (In the Balmer equation, ni = 2, and nf is just n. In the Rydberg equation, the energies may be negative (if energy is lost), while in the Balmer equation, only positive values of λ make sense.) Niels Bohr came up with a theory to explain the hydrogen spectrum, and the success of the Rydberg formula at reproducing the experimentally observed lines. He postulated that the electron in a hydrogen atom is only allowed to take on certain energy values. Another way of stating this is to say that he postulated that the energy in the atom is quantized. The allowed energy values are known as energy levels, and are associated with a quantum number, n. Bohr also postulated that an electron can change from one energy level to another by emitting or absorbing energy in the form of a photon. [Although other parts of Bohr's model are no longer part of atomic theory, these two principles-that the energy levels of an atom are quantized, and that the atom emits radiation when it goes from a higher to a lower energy level-were an important step in understanding the hydrogen spectrum, and are part of the current atomic theory.] In Bohr's theory, the atoms of hydrogen are normally in the lowest energy level, n = 1. The atom can absorb energy from an electrical discharge, which causes the electron to make a transition ("jump") into a higher energy level (n = 2, 3, 4...). Then, the energy will be reemitted in the form of electromagnetic radiation (light), as the electron changes (or "jumps down") into any of the lower energy levels. The second part of the process, in which the electrons emit energy on their way to a lower energy level, is depicted in the diagram below. Each arrow represents one of the possible transitions an electron might make. The Balmer series consists of the transitions hat end at the level n = 2; the energy involved in these jumps happens to fall within the range of wavelengths that we can detect with our eyes (the visible portion of the spectrum). The energy of the photon emitted in a given transition is equal to the difference in energy between levels: (for example where ν is the frequency of the photon: ν = c/λ, so Ephoton = hc/λ Since the atom can only occupy certain "allowed" energy levels, there is a limited number of transitions that can be made. Each of these corresponds to a specific wavelength, and it is only these allowed wavelengths that are seen in a line spectrum. Elements other than hydrogen are more complicated because of the additional particles present (the most common isotope of hydrogen is composed of just one proton and one electron!). However, the same general principles apply: only certain energies are allowed, and the wavelengths of light present in an emission spectrum correspond to transitions between these allowed levels.

Experiment 9 Thermochemistry: Determination of the Heat of Neutralization thermal chemistry deals with what? https://www.youtube.com/watch?v=rdY41FPI9iE

A chemical reaction is often accompanied by a heat change. Thermochemistry deals with the experimental measurement and calculation of such heat changes. The heat change that accompanies the reaction of one mole of substance is designated by the symbol Q. In an exothermic reaction, heat is evolved, and Q, by convention, is a negative quantity. If heat is absorbed, the reaction is endothermic and Q is a positive quantity. Heat changes for chemical reactions are usually given in calories or joules. A calorie is the quantity of heat required to raise the temperature of one gram of water one degree centigrade and one calorie equals 4.18 joules. When the heat change for a reaction is measured under conditions of constant pressure, as is the case with most chemical reactions open to the atmosphere, it equals a state function of the system called the enthalpy change, ∆H see notes

a solution is?

A solution is a homogeneous mixture. A solution forms when one substance, the solute, dissolves in another, the solvent, to form such a mixture. In this experiment, the solutes are either ionic or covalent compounds and the solvent is water

EXPERIMENT 11 Atomic Spectra and Atomic Structure An emission spectrum https://www.youtube.com/watch?v=955snB6HLB4 report http://faculty.ccbcmd.edu/~cyau/122%2010.0%20Atomic%20Spectroscopy%20AUG%202013.pdf

An emission spectrum is produced when electromagnetic radiation is given off rather than absorbed. A prism or diffraction grating can be used to separate the light given off into its component wavelengths. The emission spectrum from the sun is continuous; the visible part of this spectrum is a continuous range of colors commonly known as a rainbow. Different colors correspond to different wavelengths of light; the visible spectrum extends from about 400 nm (violet light) through about 700 nm (red light). When a gas absorbs energy from an electrical discharge, it can also emit electromagnetic radiation. However, for gaseous elements, the emission spectrum produced is not continuous. Rather, only a few, separated wavelengths make up the spectrum, with gaps in between, so that it appears as a series of lines. This type of emission spectrum is known as a line spectrum

Lab 1 Beam Balances the triple beam balance can measure mass the nearest what of a gram? the quadruple beam balance can measure mass to the nearest what of a gram?

Beam Balances The triple beam balance can measure mass to the nearest tenth of a gram (0.1 g). The quadruple beam balance can measure mass to the nearest one hundredth of a gram (0.01 g). Both balances are useful for measuring large quantities of material or when only approximate amounts of material are required. They are fairly rugged and easy to use. The object to be measured is placed on the pan and the weights are systematically adjusted on the beams until balance is achieved. For example, the three arms of the triple beam balance are calibrated from 0-100, 0-10, and 0- 1.0 grams. First the weight on the 0-100 arm is moved along the beam in 10 gram increments until the increment of weight exceeds the object weight by one unit. The weight is then returned to the next lower value. This procedure is repeated with the weights on the 0-10 gram arm and the 0-1- 0 gram arm until the balance point is reached. An object weighing 34.7g would have the weight on the 0-100 g arm set at 30, the weight on the 0-10 g arm set at 4, and the weight on the 0-1.0 g arm set at 0.7 when at balance.

EXPERIMENT 12 Determination of a Chemical Formula by Job's Method Beer's Law

Beer's Law, A = εlc, states that the light absorbed by a chemical species in solution depends directly on the concentration of that species In this experiment, Beer's Law is used as a means of determining the stoichiometry of a reaction. When solutions of Fe3+ and SCN- , both colorless ions, are mixed together, a reaction occurs that results in a red solution. This reaction corresponds to the formation of a new substance composed of iron and thiocyanate. An equation for the reaction is m Fe3+ + n SCN- → Fem(SCN)n (3m-n) where m and n are respectively the moles of Fe3+and SCN- that react. If the number of thiocyanate ions that react with each iron ion can be determined, the correct formula of the product and the stoichiometry of the reaction can be deduced. Since only the product is colored, spectrophotometric methods are suggested as a way of determining the amount of product in solution. see notes

Burets The proper use of the buret involves what? if the buret has air bubbles what can be said?

Burets Burets are commonly used where volume, measurements to the nearest 0.01 mL, are required. The burets used in this course are calibrated in 0.10 mL increments and have 50 mL capacities. The proper use of the buret involves the following steps. (1) Clean the buret. (2) Rinse the buret with 5-6 mL of distilled water. To thoroughly rinse a buret, it should be rolled on its side until all surfaces have been wet. The stopcock is then opened and the buret is drained. (3) Rinse the buret with 5-6 mL of the solution to be used in the buret. (4) Fill the buret with solution. When filled, the buret should be drained until no air bubbles remain above or below the stopcock. If air bubbles are present, the dispensing of solution will not be quantitative. (5) Place theburet vertically in a buret clamp supported by a ring stand. (6) Record the initial buret reading to the nearest 0.0l mL. To read the buret, first note that the zero calibration line is at the top and the 50mL calibration is at the bottom of the buret. Volume readings are recorded before and after liquid is dispensed through the stopcock. The difference in these measurements gives the volume of liquid used. The surface of the liquid in the buret is curved, not flat, due to the surface tension of the liquid. When recording a volume, read the liquid level at the bottom of the curved surface or meniscus. A blackened card placed behind the buret usually helps to improve the visibility of the meniscus

Compounds are also classified by their solubility properties; they may be soluble or insoluble when mixed with solvents

Compounds are also classified by their solubility properties; they may be soluble or insoluble when mixed with solvents. Water, the solvent in this experiment, is the most common solvent. Ionic and covalent compounds can be distinguished by their behavior in water (aqueous) solution. Soluble ionic compounds dissolve in water to produce ions in solution; soluble covalent compounds dissolve in water to produce molecules in solution. For example, NaCl dissolves in water to give a solution containing Na' cations and Cl- anions, and CH30H dissolves in water to give a solution containing CH3OH molecules. These solution processes can be represented by the equations:

compounds are what? Covalent compounds an ionic compound

Compounds are substances made up of two or more elements in a definite proportion by weight. They can be classified as covalent or ionic depending on the nature of the particles of which they are composed. All compounds are electrically neutral. Covalent compounds are made up of molecules, which are electrically neutral. Ionic compounds are composed of ions, which are charged species. Charged species can be positive or negative; positive ions are called cations, negative ions are called anions. For an ionic compound to be neutral the total positive charge on the cations must equal the total negative charge on the anions. For example, NaCI contains both Na+ and Cl- ions in equal amounts. Na2CO3 is composed of two Na' ions for each C03' - ion; similarly MgI2 consists of one Mg' for every two I- ions.

density determination

Density Determination Density is a basic property of all pure substances. It is defined as mass (M) per unit volume D=M/v

Dumas method

Dumas developed a simple procedure in which the pressure, volume, temperature, and weight of a gaseous sample could be easily measured, and its molecular weight calculated. In the procedure, an excess of a volatile liquid is placed in a flask of known weight and heated at constant temperature, in a water bath, until all of the liquid vaporizes. This drives both the air and any excess vapor out of the flask. The flask then contains vapor at a known T (temperature of the water bath), P (atmospheric pressure), and V (volume of the flask). To determine the mass of the vapor, the flask is cooled and reweighed. The increase in weight represents the weight of the vapor. The Dumas method is used in this experiment to determine the molecular weight of an unknown volatile liquid

message This procedure involves several new techniques: quantitative precipitation, the quantitative transfer of precipitates and filtration, described above, and the use of the Bunsen burner

Finally, the filtered PbCrO4 precipitate can be washed free of impurities with water, dried at 100-120° without loss or decomposition, and weighed. The weight of Pb in the precipitate can be calculated from the weight of the precipitate and the percent by weight of lead in PbCrO4. Since all of the lead in the precipitate came from the original sample, the percent of lead in the sample can be calculated from the weight of lead in the precipitate and the total weight of the sample.

The Bunsen burner

Gas enters the burner at the base through a needle valve, which is controlled by turning, and passes up the barrel of the burner. Air is pulled in through air intake holes, and a combustible mixture of air and gas exits at the top of the burner. The amount of air in the mixture is controlled by rotating the barrel to open or close the air holes. The proper method for using the burner is to close the air holes, and open the gas inlet. A striker is used to ignite the gas coming out of the burner. The flame will be yellow due to insufficient air. The gas is adjusted until the flame is about 6" high. The air intake holes are then opened until the flame turns blue and a cone-shaped region appears in the flame. A yellow flame indicates the gas is not burning completely. A blue flame indicates complete combustion and provides the hottest flame. The hottest portion of the flame is just above the inner cone

Graduated Cylinders how many capacities are Graduated Cylinders available in? what are the degree of accuracy?

Graduated Cylinders Graduated cylinders are available in many capacities from 5 mL to 2000 mL. Each size has different calibration units and can be read with different degrees of accuracy. Small sizes can at best be read to + 0.1 mL while larger sizes can only be read to ± 1 or 2 mL. Graduated cylinders are not used for very accurate quantitative measurements. They are convenient for measuring and transferring liquids where exact volumes are not required.

Gravimetric quantitative analysis for an analysis to be reliable, the following conditions must be met:which are the more

Gravimetric quantitative analysis is one method for determining the amount of an element or ion in a substance. However, for an analysis to be reliable, the following conditions must be met: First, a chemical reaction resulting in the formation of a single pure solid or precipitate containing the element or ion to be analyzed must be available. The precipitate must have a definite and known chemical composition. Second, the precipitate should have a very low solubility. The material to be analyzed must be completely removed from solution if the analysis is to be quantitative. Third, a means of collecting the precipitate must be available so it may be weighed. Fourth, the precipitate must be free of impurities such as the solvent or other reagents present in the solution which may add to its weight. To remove impurities a precipitate is usually washed and dried. The procedure for the gravimetric analysis of lead, although subject to some interferences, satisfies these general requirements. The chemistry involved in the analysis is described below.

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In this experiment, the amount of lead, Pb, in a soluble salt is determined by a gravimetric quantitative analysis, i.e., an analysis performed by weighings. The procedure involves dissolving a known weight of the lead salt in water, adding a reagent to precipitate the lead from solution, collecting the precipitate, and weighing it.

spectroscope

In this lab, you will use a spectroscope to observe the emission spectra of several elements. The spectroscope is used to measure the wavelength associated with each line in the spectrum. It consists of a box with a slit at one end for letting light in, and a diffraction grating, which, like a prism, splits up the incoming light into its component colors. When you look through the opening at the other end of the spectroscope, you will see the line spectrum on a numerical scale. This scale allows you to measure the wavelength of each line in the spectrum You will observe the spectrum from gas discharge lamps, as well as from flame tests of various salts. You will note down the colors you see and the numerical value for the wavelength, and use your observations to determine a value for the Rydberg constant. In the flame tests, the atoms absorb energy from the flame, then emit energy in the form of light, just as the atoms inside the lamp absorb electrical energy and then emit photons. Finally, you will use your observations from the flame tests of known cations to identify an unknown.

Charged particles ionic and covalent

Insoluble compounds do not dissolve in water. Charged particles can carry charge. Therefore an electric current, a flow of electrons, can be conducted by solutions containing charged particles. Since ionic compounds form ions in solution, solutions of ionic compounds conduct a current when a voltage is placed across such a solution. Solutions of covalent compounds do not contain charged particles and cannot carry a charge. An electric current will not be conducted when a voltage is placed across a solution of a covalent compound. (Some covalent compounds dissolve in water and produce ions through reactions with the solvent. These covalent substances will be considered in later experiments.) One method of determining if a water soluble compound is ionic or covalent is to prepare a solution of the compound and observe if a current flows when a voltage is imposed across https://www.youtube.com/watch?v=FKyDgf9_wqk

lab 6 Observations of Chemical Reactions defined acid, base, salt

Ionic compounds can be further classified as acids, bases, or salts. Acids are compounds that produce H+ ions in solution. Three common acids are HCl (hydrochloric acid), H2SO4 (sulfuric acid), and HNO3 (nitric acid). Bases are compounds that produce OH- ions in solution. Two common bases are NaOH (sodium hydroxide) and KOH (potassium hydroxide). Salts are ionic compounds that do not contain H+ or OH- , such as NaCl, MgCO3, or Na2SO4. This experiment deals mainly with solutions of salts and the chemical reactions that occur when different salt solutions are mixed. When solutions containing ions from different soluble salts are mixed together, the ions may react to form different substances. That is, one set of substances, called the reactants, is changed into substances with different properties, called the products. A reaction may be represented by a chemical equation, which is usually written in the form reactants → products

experiment 5 Determination of the Percent by Weight of Lead qualitative or quantitative analysis of a substance https://www.youtube.com/watch?v=6dcGaTxg-DY gRAVITAL ANALIST CAL http://www.wiredchemist.com/chemistry/instructional/laboratory-tutorials/gravimetric-analysis

Many experiments performed in this laboratory involve the study of chemical systems to learn pertinent facts about them; this may involve the qualitative or quantitative analysis of a substance. Qualitative analysis considers what elements, compounds, or ions are present in a substance. Quantitative analysis determines the amount of a particular component that is present in a sample.

EXPERIMENT 8 Determination of Molecular Weight by Gas Density Measurements one of the simplest method for determining molecular weight is based on what? https://www.youtube.com/watch?v=0UJXa9Hd88I

One of the simplest methods for determining molecular weights is based on the ideal gas law, PV = nRT where P is the pressure in atmospheres, V is the volume in liters, n is the number of moles, T is the temperature in K of a gas sample, and R is the gas constant, which is equal to 0.0821 L atm/K mol. If P, V, and T for a gaseous sample can be measured, the gas law can be used to calculate the number of moles of gas present.

EXPERIMENT 10 Spectra and Beer's Law colorimetry spectrophotometry https://www.youtube.com/watch?v=XtwY6pxnbGU

One way to determine the identity and concentration of a compound in solution is to observe its color and the intensity of its color. This technique is called colorimetry. For example, compound A gives a blue solution, compound B a pink one. Information about the concentration of the species in solution is obtained by observing the intensity of the color of the solution which is directly related to the concentration of the species in solution. Simple colorimetric measurements may be made with the unaided eye which is very sensitive to both colors and intensity of colors. If only very small color changes are involved, or if more than one colored species are present in solution, a more accurate way to measure color and intensity is necessary. Such a method is called spectrophotometry

Pipets are used for what? transfer pipets measuring pipets

Pipets are used to dispense a known volume of solution quickly and accurately. Two types of pipets exist: transfer pipets and measuring pipets. Each type is available in many capacities. Measuring pipets are calibrated in small increments of the total capacity of the pipet. Each size has different calibration units. They are read in the same manner as burets. Transfer pipets have only one calibration mark. They deliver a set volume of liquid. When using either type of pipet, liquid is drawn up the pipet by using a rubber suction bulb - NEVER BY MOUTH - until the level is above the desired graduation mark. The liquid is then carefully lowered, by releasing the suction, until the bottom of the meniscus just coincides with the graduation mark. Then the liquid is dispensed into the desired container by completely releasing the suction and allowing the pipet to drain. Many pipets are calibrated "to deliver" a specific volume when filled and drained completely. A drop usually remains in the tip of the pipet, again due to surface tension, and should not be forced out. Pipets that hold l mL or more deliver the marked volumes with an error of ±.01 mL.

Precision and Accuracy

Precision and Accuracy Since errors are present in any measurement it is often necessary to determine the reliability of the data. Two terms used in such an evaluation are precision and accuracy. A series of determinations are precise if there is good agreement among the individual values of the measured quantity. A result is accurate if it agrees well with the true value for that measurement. It is possible for measurements to be accurate but have poor precision (due to large random errors). Alternatively, measurements can be precise but not accurate (due to large systematic errors). The following data taken on an analytical balance illustrate these points

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Quantitative information about the concentration of compounds in solution can be obtained because it is found that the absorbance of a solution is proportional to the molar concentration of the solution and the path length through which the light travels. This may be expressed as A = ε l c (1) where A = absorbance c = molar concentration (moles/liter) l = path length (in this experiment = 1 cm) ε = a proportionality constant called the molar absorption coefficient which depends on the material being stud

filtering quantitative filtration

The PbCrO4 precipitate forms because it is very insoluble in water. Its solubility is only 4.6 x 10−1 g/L at 25°C. Since the solubility of the salt is low, all of the lead ions present in solution will precipitate. The solid PbCrO4 can be removed from solution by filtering. Filtering involves pouring a solution and precipitate onto a filter paper, which retains the solid and allows the liquid to pass through. Quantitative filtration requires that all the precipitate be transferred to and held by the filter. If the particles of the precipitate are very small they may pass through the pores of most filters. The particle size of many precipitates can be increased by digestion or heating. In this procedure, small particles dissolve in the hot solution and then reprecipitate on the larger particles causing a net increase in particle size without loss of precipitate.

The analytical balance can measure mass to the there is one of the military?

The analytical balance can measure mass to the nearest tenth of a milligram (0.1 mg or 0.0001 g). It is a more sensitive instrument than the beam balance, and is used for measuring small quantities of material or when very accurate weightings are required.

Beer-Lambert Law see notes

The expression is known as the Beer-Lambert Law. It has the mathematical form of a straight line, y = mx + b, where y = A, x = c, m = εl and b = 0. A plot of absorbance, A, versus concentration, c, should result in a straight line. Such a graph is called a Beer's Law plot (Figure 8.3). The usual method of employing Beer's Law is to measure the absorbances of various concentrations of a compound at the wavelength at which the absorption of that compound is a maximum In this experiment, the absorption spectrum (absorbance vs. wavelength) of a complex ion of copper, Cu(NH3)4 2+ , is determined. The complex ion is prepared by adding an excess of NH3 to a solution containing Cu. Cu2+ + 4 NH3 → Cu(NH3)4 2+ (2) A Beer's Law plot (absorbance vs. concentration) for Cu(NH3)4 2+ at the wavelength where the complex ion has a maximum absorbance is then constructed. In order to construct the Beer's Law plot it is necessary to calculate the concentration of theCu(NH3)4 2+ in each of the prepared solutions. The concentration unit used is molarity, M, which is defined as the number of moles of solute (n) per liter of solution (V).

see notes

The reactants are shown on the left, the products on the right, and the arrow is used to indicate the direction of chemical change. Only species that actually change are usually written in a chemical equation. Reactants and products may be characterized by physically observable quantities such as color, odor, and state of matter (solid, liquid, or gas). Careful observation of these properties often allows deductions to be made about the identity of a chemical compound and the ions present in a sample. The reactions of seven anions and one cation are to be studied in this experiment. The anions are carbonate (CO3 2− ), sulfate (SO4 2− ), chloride (Cl − ), iodide (I− ), acetate (C2H3O2 − ), nitrate (NO3 − ) and chromate (CrO4 2− ). The cation is copper II (Cu2+). It is important to learn the names, chemical symbols, and charges on these ions. Correct chemical equations describing the reactions of the ions must also be learned. These chemical reactions are described below.

volumetric flask

Volumetric Flasks The volumetric flask is used for preparing solutions. It is available in various capacities and has a single graduation mark on the neck of the flask. When filled so the bottom of the meniscus coincides with the graduation mark the volumetric flask contains the specified volume of liquid

EXPERIMENT 7 Volumetric Determination of an Unknown Chloride what is titration titrant endpoint indicators https://www.youtube.com/watch?v=3iuVXHxyB1k

Volumetric quantitative analyses are usually performed by a procedure called titration. Titration is a technique in which one reagent, called the titrant, is dispensed from a buret into a flask containing a fixed amount of a second reagent. The addition is continued until exactly enough has been added to react completely with the second reagent. End points are usually observed as distinct visible color changes in solution. The color changes are often due to substances called indicators, which are added to the solution being titrated. Indicators may be any of a variety of chemical substances that fulfill two requirements. First, the color change observed must occur at the end point of the reaction. Second, the color change must be sharp; one extra drop (0.03m1) of titrant should cause the color change to be visible. Once the end point of the titration has been detected, the concentration or composition of the unknown sample can be calculated using the concentration and measured volume of titrant used to reach the end point of the reaction, and the stoichiometry of the reaction involved.

Uncertainty in Measurements systematic errors and random errors.

When a measurement is made on an instrument there always exists some uncertainty or error in that measurement. Uncertainties or errors in a measurement are of two types== systematic error Systematic errors are those inherent in the instrument or the method used to make the measurement. They affect all results in the same direction to the same extent. For example, a systematic error would result from incorrect degree markings on a thermometer that caused all temperature readings to be low. This type of error can often be evaluated and suitable corrections can be made to the data. Random errors occur mainly because of the limitations of the instrument and of the observer in making the measurement. Estimates of correct values are always made in recording measurements from dials, meters, or calibrated glassware. These estimates occur in the last decimal place that the instrument can measure and are always subject to the judgment of the observer. Random errors usually cause the measured value to deviate from the correct value by only small amounts and positive and negative deviations of similar magnitude are equally likely to occur There are many ways to designate the uncertainty of a measurement. One which should always be used is to indicate the extent to which the instrument is capable of measuring, e.g., the triple beam balance weighs to 0.1 g, and the analytical balance to 0.0001 g. A reading designated 1.1 g indicates the reading was taken on a triple beam balance and the true weight is probably between 1.0 and 1.2 g (i.e., there is an uncertainty in the last digit of 0.1 g). To record the result as 1.1000 would be meaningless since the .1 is uncertain. The same object weighed on an analytical balance would have its weight reported as 1.1038 g. This indicates its true weight is probably between 1.1037 and 1.1039 g (i.e., there is an uncertainty in the last digit off 0.0001 g). The reading should not be recorded simply as 1.1 g since the .1 is not uncertain.

spectrophotometry

When white light is directed at a colored solution, some of the components of the white light are not transmitted through the solution. They have been absorbed by the solution. The frequencies (or wavelengths) of white light which are transmitted through the solution gives the observed color to the solution (Figure 8-1). The amount of light which is absorbed by a substance in solution is a function of the concentration of the substance in the solution. In order to do quantitative work using spectrophotometry, the light which has been absorbed by the solution must be measured. Sensitive measurements of the color and intensity of light which has been absorbed may be made with a spectrophotometer (spectro-many colors, photo-light, meter-measure). The spectrophotometer separates light into its component wavelengths, isolates a selected wavelength band, directs this band through a solution and measures the amount of light absorbed. The absorption at various wavelengths can then be recorded. A plot of the absorbance of a solution versus wavelength of incident light is called an absorption spectrum. Because most compounds have a unique spectrum, determining the spectrum is also a precise way of identifying a compound in solution. The spectrum of a compound resembles a "fingerprint."

Lab 2 Volumetric Glassware The most commonly used items of volumetric glassware are the youtube video density of solid https://www.youtube.com/watch?v=dZWIlhtUR5w weigh on balance beam pour in cylinder and note the displacement inital.final. density of liquid https://www.youtube.com/watch?v=RnSJSSCfgPc weigh on analitical and note the inital volume M/v=density

graduated cylinder, buret, pipet, and volumetric flask.

EXPERIMENT 4 In this experiment, observations will be made about the behavior of compounds in solution; specifically, observations will be made about the ability of solutions of both ionic and covalent compounds to carry an electric current. The experiment will use the analytical balance to make accurate weighings and volumetric glassware to make accurate solutions https://www.youtube.com/watch?v=emymtKPTIHk quiz http://gciscience.weebly.com/uploads/5/1/5/0/5150508/review_for_quiz_2_ionic_and_covalent_compounds_answers_to_review.pdf

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see lab 3

see lab 3

When potassium chromate, K2CrO4, is dissolved in water, two potassium ions, K+ , and one chromate ion, CrO4 2− form. This may be represented by the net ionic equation

see notes

where the (s) indicates that K2CrO4 is a solid. A soluble lead compound when dissolved in water will form anions and lead cations, Pb2+. If a weighed sample of a soluble lead salt is dissolved in water and mixed with a solution containing CrO4 2− a chemical reaction occurs and pure PbCrO4, an orange solid of known composition, forms. The net ionic equation for this reaction is

see notes Soluble fiber dissolves in water. Insoluble fiber does not. To some degree these differences determine how each fiber functions in the body and benefits your health. Soluble fibers attract water and form a gel, which slows down digestion.