Unit 1: Intro to Chemistry

From a laboratory process designed to separate water (H2O) into hydrogen (H2) and oxygen gas (O2), a student collected 10.0g of hydrogen (H2) and 79.4g of oxygen (O2). How much water was originally involved in the process? (Please record a number only) Unbalanced Chemical Equation: H2O --> H2 + O2 water decomposes into hydrogen gas and oxygen gas

89.4 g

What is the difference between a molecule and a compound?

A compound has at least 2 DIFFERENT elements (2 different kinds of atoms bonded together) A molecule has 2 or more atoms covalently bonded together, they do not have to be different kinds

define weight

A measure of the force of gravity on an object

elements

A molecule composed of one kind of atom; cannot be broken into simpler units by chemical reactions (only 1 capital letter and only 1 word long) EX: N, O, Cl, H, He, Fe

hypothesis

A testable prediction, often implied by a theory

Crystallization

a technique that results in the formation of pure solid particles from a solution containing the dissolved substance. As one substance evaporates, the dissolved substance comes out of solution and collects as crystals.

Mechanical energy

a type of kinetic energy that is due to the motion of an object

Compound particle diagram

all the same compound

Law of definite proportions

atoms combine in whole number ratios, so their proportion by mass will always be the same EX: H2O is always made up of 2 atoms of H and one atom of O. The mass ratio of O to H in water is always 16:2 or 8:2

Chemically combined

chemical reaction, there is no (+) sign EX: compounds such as Salt (NaCl)

Identify as an element, compound, homogeneous mixture, or heterogenous mixture: Carbon Dioxide

compound

Element or Compound: MgCl2

compound (Two capital letters)

Atom, element, compound, molecule: CO2

compound (two different elements) and molecule (two atoms covalently bonded)

Element or compound: sulfur hexachloride

compound (two words)

Extensive physical property

depends on the amount of matter in the substance EX: size, mass, length, shape, volume

Intensive physical properties

does not depend on the amount of matter in the substance EX: color, smell, ductility, phase, malleability, boiling point, melting point, and density

Identify as an element, compound, homogeneous mixture, or heterogenous mixture: Helium

element

Element or compound: He

element (one capital letter)

Element or compound: Magnesium

element (one word)

Element or compound: argon

element (one word)

Atom, element, compound, molecule: Br2

element and molecule (2 or more atoms covalently bonded together)

pure substances

elements and compounds (all particles look the same)

Homogenous or heterogenous: chocolate chip cookie

heterogeneous

Identify as an element, compound, homogeneous mixture, or heterogenous mixture: Chex mix

heterogenous mixture (you can see the different parts)

Homogeneous or heterogenous: sweet tea

homogenous

magnetism

ideal method for separating mixtures of two solids with one having magnetic properties. Some metals like iron, nickel & cobalt have magnetic properties while gold, silver, and aluminum do not. This property can be used to separate them from other solids.

Law of multiple proportions

if two elements can combine to form more than one compound, the mass of one element, which combines with a fixed mass of the other element, will always be whole number ratios; compounds of differing mass ratios of the same element will have different properties EX: carbon dioxide (CO2) and carbon monoxide (CO)

Sublimation

is a process in which some solids, on heating, are transformed directly to gas without passing through the liquid phase. This technique can be used to separate a mixture of solids, one of which can undergo sublimation. The vapors are then cooled separately to get the sublimed solid back, a process called deposition.

electrolysis

is a way of separating a compound by passing an electric current through it; the products are the compound's component ions.

Chromatography

is often used when the dissolved substances are colored, such as inks, food colorings and plant dyes. This process works because some of the colored substances dissolve better than others, so they travel further up the paper.

decantation

is simply to pour off the upper liquid layer. Most often used to separate a liquid from an insoluble solid where the solid stays in the bottom of the container.

Physically combined

just in the same place, look for the (+) sign EX: mixtures such as salt water (NaCl + H2O)

Thermal energy

kinetic energy and is heat energy and is the vibration or movement of particles

Electrical energy

kinetic energy that is from flow of electric charge

Sound energy

kinetic energy that is vibration transferred through an object in a wave to produce sound

Homogenous mixtures

look the SAME throughout, particles are evenly mixed

law of conservation of matter

matter cannot be created nor destroyed, can only change forms EX: melting ice, the amount of substance is still in the container, only it's state has changed

Mixture of elements particle diagram

not touching - physically combined

Mixtures are ________ combined while compounds are _________ combined

physically chemically

gravitational energy

potential energy stored in an object's height

elastic energy

potential energy stored in elastic objects

chemial energy

potential energy that is store in bonds of atoms and molecules

nuclear energy

potential energy that is stored in atoms' nuclei

Filtration

used to separate heterogenous mixtures composed of solids and liquids. Process involves using a porous barrier to separate the solid from the liquid passes through leaving the solid in the filter paper. Depends on the size of the particles

Centrifugation

used to separates solids from liquids, or separates two immiscible liquids (liquid that do not mix well), on the basis of density

Percent composition

% mass = (mass of element in 1 mole of the compound) / (molar mass of the compound) x 100% OR mass percent = (mass of solute / mass of solution) x 100%

A student carefully placed 15.6g of sodium (Na) in a reactor supplied with an excess of quantity of chlorine gas (Cl2). When the reaction was complete, the student obtained 39.7g of sodium chloride (NaCl). Calculate how many grams of chlorine gas (Cl2) reacted. Unbalanced Chemical Equation: Na + Cl2 --> NaCl sodium combines with chlorine gas to create sodium chloride.

24.1 g

Atom, element, compound, molecule: He

Element and atom

Atom, element, compound, molecule: O3

Element and molecule (2 or more atoms covalently bonded)

What type of pure substance cannot be broken down any further?

Elements

Compare observation and inference

Observation: description of something you can see, touch, feel, hear, and taste Based on facts Inference: a guess about an object or outcome on your observations Based on an educated guess

compounds

2 or more DIFFERENT elements CHEMICALLY combined (two or more words long (unless common name like water or sugar), and two capital letters) EX: H2O (water), CO2 (carbon dioxide), C6H12O6 (glucose)

molecule

2 or more atoms bonded together

In an experiment, 10.00g of red mercury (II) oxide (HgO) powder is placed in an open flask and heated until it is converted to liquid mercury (Hg) and oxygen gas (O2). The liquid mercury has a mass of 9.26g. What is the mass of the oxygen formed in the reaction? (Please record a number only) Unbalanced Chemical Equation: HgO --> Hg + O2 mercury (II) oxide decomposes into liquid mercury and oxygen gas

0.74 g law of conservation of matter states that matter cannot be created or destroyed. We know on the reaction side that there is 10.0 g of HgO, that means the product side it must add up to 10.0 g total in the end. We know that Hg has a mass of 9.26 g. So if we take 10.0g-9.26 g we get 0.74 g which is our mass of oxygen. The mass can change in the forms but the matter cannot.

Bicarbonate of soda (sodium hydrogen carbonate) is used in many commercial preparations. Its formula is NaHCO3. Find the mass percentages (mass %) of Na, H, C, and O in sodium hydrogen carbonate.

1. Find the atomic masses for the elements in the Periodic Table: Na = 22.99 H = 1.01 C = 12.01 O = 16.00 2. Determine how many grams of each element are present in one mole of NaHCO3: 22.99 g (1 mol) of Na 1.01 g (1 mol) of H 12.01 g (1 mol) of C 48.00 g (3 mole x 16.00 gram per mole) of O 3. Find the mass of one mole of NaHCO3: 22.99 g + 1.01 g + 12.01 g + 48.00 g = 84.01 g 4. Find the mass percentages: mass % Na = 22.99 g / 84.01 g x 100 = 27.36 % mass % H = 1.01 g / 84.01 g x 100 = 1.20 % mass % C = 12.01 g / 84.01 g x 100 = 14.30 % mass % O = 48.00 g / 84.01 g x 100 = 57.14 %

Question/Problem

After making an observation, ask a question about that observation. The second step of the scientific method.

define matter

Anything that has mass and takes up space

Explain the difference between an atom and a molecule

Atom: smallest part of an element that is still that element Molecule: two or more atoms joined and acting as a unit

Why is sugar considered a compound?

Because it has a fixed composition

Atom, element, compound, molecule: C4H10

Compound (2 different elements) and molecule (2 atoms covalently bonded)

Element or compound: H2SO4

Compound (2 or more capital letters)

quantitative data

Data associated with mathematical models and statistical techniques used to analyze spatial location and association.

law of conservation of energy

Energy cannot be created or destroyed, only changed from one form to another EX: In a speaker, electrical energy is converted into sound energy, or in a generator mechanical energy is converted into electrical energy

Kinetic Energy

Energy of objects in motion (Objects being waves, electrons, molecules, substances

Potential energy

Energy stored in an object; due to the object itself or its position

T/F: Compounds can be physically broken down

False! Compounds can only be broken down chemically

Water (H2O) always has 2 atoms of hydrogen and 1 atom of oxygen. We say that this means water has a _____ composition

Fixed

Which of the following is an element? H2O4 CH4 He NaCl

He

Identify as an element, compound, homogeneous mixture, or heterogenous mixture: Gatorade

Homogenous mixture

control group

In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

qualitative data

Information describing color, odor, shape, or some other physical characteristic

Radiant energy

Kinetic energy and is light energy that is electromagnetc energy that travels in transverse waves

define density

Mass per unit volume

Chemical properties

Reactivity - how a substance reacts with another substance, measured by changing the substance; meaning it goes from one substance and turns into an entirely new substance EX: toxicity, flammability, corrosivity, reactivity

Copper (II) Sulfate is a blue powder. When copper (II) sulfate is dissolved in water, the water turns blue. How would the blue water be classified?

Solution

Homogenous solutions

Solutions: one substance dissolved into another EX: koolaid, salt water, sweet tea

Classify a solid

The molecules that make up a solid are arranged in a regular, repeating patterns. They are held firmly in place but can vibrate within a limited area. Has a definite shape & volume

Atom

The basic particle of which all matter, everything, is made

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

Law of conservation of matter (Math)

The law states that in a reaction, matter can not be created or destroyed. This means that the mass of all reactants in a reaction will be equal to the mass of all the products. The mass may change in forms in the reaction but the matter is neither created nor destroyed.

Classify a gas

The molecule that make up a gas fly in all direction at great speeds. They are so far apart that the attractive forces between them are insignificant Has an indefinite shape and volume

Classify a liquid

The molecules that make up a liquid flow easily around one another. They are kept from flying apart by attractive forces between them. Liquids assume the shape of their containers. Has a definite volume

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

Physical property

a characteristic that can be observed or measured without changing the identity of the substances, described through observations with the senses EX: color, malleability, ductility, solubility, density, hardness, shape, temperature, mass, melting point

mixtures

substances NOT chemically combined, they are PHYSICALLY combined!! Can be homogeneous or heterogeneous

Heterogenous mixture

substances unevenly mixed, looks different all over EX: trail mix, water and oil

evaporation

technique used for separating a mixture (solution) of a soluble solid and solvent. The process involves heating the solution until the solvent turns into a gas leaving behind the solid residue.

distillation

technique used to separate homogeneous mixtures based on differences in boiling points of substances involved. This technique is best for separating a liquid from a solution where the vapor that results from boiling is then collected by condensation.

define mass

the amount of matter in an object

what is chemistry?

the study of matter and the changes it undergoes