AP Chem: States of Matter – Flashcards

1. Substance changes form or state only. Boiling, melting, freezing, dissolving, grinding, cutting
2. Where new substances are formed with new chemical and physical properties. Oxygen and hydrogen form water; sodium and chlorine form salt (sodium chloride)

Gas: neither definite shape nor volume

Liquid: definite volume; takes shape of container

Solid: definite size and shape

A sharply defined, uniforme region in a mixture.

Examples- oil and vinegar in salad dressing; ice and water in a frozen pond

The mass of a unit volume of a substance.

Density = mass/volume

g/mL g/L kg/L

Density = mass/volume

density 10 g/5 mL = 2 g/mL

A substance composed of identical atoms.

gold, silver, oxygen, hydorgen, lead, chlorine, helium, iron, copper, fluorine, arsenic

Substance composed of two or more different elements chemically combined. For example:

Water - H₂O

Salt - NaCl

Sugar - C₆H₁₂O₆

Ammonia - NH₃

A combination of substaces held together by physical means.

(Dirt, milk, soup, saltwater, granite)

Homogeneous mixtures are uniforme in composition. (Air, metal, alloy, salt water)

Hetergeneous mixtures are not uniform in composition. (Dirt, spaghetti sauce)

1. Ba
2. Be
3. Pt
4. As
5. Sn

1. Na
2. K
3. Ca
4. H
5. Mg

1. Iron
2. cobalt
3. Nickel
4. Copper
5. Zinc

1. Ag
2. Au
3. Hg
4. Al
5. Pb

1. Carbon
2. Silicon
3. Nitrogen
4. Phosporous
5. Oxygen

1. S
2. F
3. Cl
4. Br
5. I

1. Helium
2. Neon
3. Argon
4. Krypton
5. Uranium

The sum-total of mass and energu remains constant in a reaction but mass and energy may be interconverted.

E = mc²

E= energy; m = mass

c= speed of light

Sand - mixture

Air - mixture

Gold - element

Water - compound

Salt - compound

Hydrogen - element

1. Properties which can be observed without changing the substance into something different. Color, odor, hardness, density, luster, state, conductivity, solubility, boiling and melting points.
2. A chemical property is observed when a substance changes into a new substance. Iron forms rust in air and water; gasoline burns in oxygen.

Pressure is force per unit of area

;

1 atmosphere= 760 torr

= 760 mm Hg

= 101.3 kilopasca;s

= 14.7 pounds/square inch

1. An instrument, invented by torricelli in 1643, which measures atmospheric pressure. An evacuated glass tube in which a column of mercury rises or falls with change in pressure.
2. An instrument used to measure pressure of gases in a closed container.

1. Matter is composed of very small particles; a gas is mostly empty space.
2. Particles are in constant random motion.
3. Collisions are elastic

A mixture of a gas A & B:

(R_A)(MW_A)^1/2 = (R_B)(MV_B)^1/2

MW_A,MW_B = Molecular weights

R_A, R_B = Rates of Diffusion

(Light gases diffuse faster)

V₁/T₁ = V₂/T₂

Pressure and amount of gas are constant

V = volume

T = Kelvin

Use Charles' Law,

V₁/T₁ = V₂/T₂

10/300 = V₂/400

V₂ = 13.3 L

P₁;x V₁ = P₂ x V₂

Pressure and volume are inverse if temperature and amount of gas are constant

P = pressure

V = volume

Use Boyle's Law

P₁ x V₁ = P₂ x V₂

25 x 800 = 400 x V₂

V₂ = 50 L

P₁V₁/T₁ = P₂V₂/T₂

Amount of gas is constant

P = pressure

V = volume

T = kelvin

In a gas mixture, the total pressure equals the sum of the partial pressures of each component

P_total = P₁ + P₂ + P₃ ...

PV = nRT

P = pressure (Atmospheres)

V = volume (Liters)

n = # of Moles

R = 0.0820 L-ATM/MOL-K

T = temperature in K

Use the Ideal Gas Law

PV = nRT

;

(4 atm)(20 L) = n(0.082)(400)

n = 2.44 moles

1. Standard temperature (0° C or 273 K) and standard pressure (1 atmosphere or 760 torr)
2. When only gases are involved in a reaction, the volumes of reactants and product are in a small, whole number ratio.

1. Under the same conditions of temperature and pressure; equal volumes of gases contain equal numbers of moles.
2. 22.4 L

According to Gay-Lussac's Law the volumes of gases are in direct proportion to the coefficients in the equation.

H₂ : 3/6 L = NH₃ : 2/x

x = 4L of ammonia

The change from a solid to a vapor without the forming of a liquid

Compounds which show sublimation

(CO₂, I₂)

When a molecule gains enough kinetic energy to overcome the intermolecular attractive forces within a liquid, it escapes the surface and becomes gas.

1. For a liquid in a closed container; when the rates of evaporation (liquid to gas) and condesation (gas to liquid) equalize: the concentration of each is stable.
2. In a closed container where opposing changes are taking place at equal rates; the concentration of all components remains constant.

The temperature at which a liquid phase becomes a gas phase when vapor reaches atmospheric pressure.

Pressure = 1 atm

1. The temperature above which the liquid phase of a substance can no longer exist.
2. Minimum pressure required to liquify a gas at its critical temperature

The temperature at which the solid and liquid phases co-exist

1. The amount of energy required to change a gram of substance from liquid at its melting point. (Water - 80 calories/gram)
2. The amount of energy required per gram to change a liquid to gas at its boiling point. (Water - 540 calories/gram)

1. The only temperature and pressure combination at which the 3 phases of a substance (solid, liquid and gas) can co-exist at equilibrium
2. The pressure the gas phase exerts on its liquid phase in a close container. This pressure varies with temperature.

The temperature at which the vapor pressure over a liquid reaches atmospheric pressure. The substance boils (liquid to gas)

1. Heat of vaporization of water is 540 cal/g

10g x 540 cal/g = 5400 cal

2. Heat of fusion of water is 80 cal/gram

(0.5 grams)(80 cal/gram) = 40 cal