Chemistry Gases and Kinetics/Equilibrium Unit Test

Kinetic Molecular Theory

explains the behavior of an ideal gas in terms of the motion of their particles

describes the motion of atoms and molecules, motion is defined by conditions of temperature and pressure, gases that follow KMT are called ideal gases

Ideal Gas

a theoretical gas that is under conditions of high temperature and low pressure, closely adheres to kinetic molecular theory

Follow PLIGHT"

Real Gas

all gases that exist in real life, are not ideal

Temperature

a measure of average kinetic energy

Pressure

the force of pushing or squeezing measured in atmospheres (atm) or kilo pascals (kPa)

Volume

thee amount of space an object takes up

Boyle’s Law

at constant temperature, as volume of a gas increases, the pressure decreases (and vice versa)

Charles’ Law

at constant pressure, as temperature increases, pressure also increases

Gay-Lussac’s Law

at constant volume, as temperature increases, pressure also increases

Combined Gas Law

shows the relationship between pressure, volume, and temperature of a gas

Avogadro’s Law

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules regardless of their identity

Average Kinetic Energy

measure of how quickly particles are moving, measured as temperature

Vapor Pressure

how badly a liquid wants to become a vapor, the pressure that a vapor exerts, related to boiling point and ability to evaporate

willingness of a solid or liquid to evapore and become a gas

Normal Boiling Point

the temperature at which a substance boils at standard pressure

Phase Equilibrium

a state where two phases are at equilibrium with each other (Solid and liquid: rate of freezing same as rate of melting) (Liquid and gas: rate of evaporation same as rate of condensation)

Rules of Kinetic Molecular Theory

• Gases contain particles that are in constant, random, straight-line motion

• When gas particles collide with each other and/or the walls of the container, there is no loss of energy, just a transfer from one to another. These are called elastic collisions

• Gas particles are very small and the space between them is very large. For this reason the volume of individual particles is negligible. The volume of the container is considered the volume of the gas

• Gas particles do not attract each other (they act as if there are no IMFs because they’re so far apart)

• The temperature is directly proportional to the temperature of the sample in Kelvin or Celsius

How do particles in gases move?

in a constant, random, straight line motion

What are elastic collisions?

when gas particles collide with each other and/or the walls of the container, there is no loss of energy, just a transfer from one to another

What is considered to be the volume of a gas?

the volume of the container

Why is the volume of a container considered to be the volume of the gas?

because gas particles are very small and the space between them is very large, making the volume of individual particles insignificant

Why do gas particles not attract each other?

because they are so far apart

What does PLIGHT stand for?

Pressure Low, ideal gas, high temperature

What is pressure, in terms of gases?

how hard the gases bounce off the walls of the container, force of pushing measured in atmospheres, kiloPascals, millimeters of mercury, and torr

What is pressure measured in?

• atmospheres (atm)

• kiloPascals (kPa)

• millimeters of mercury (mmHg)

• torr

What is standard pressure in atmospheres (atm)?

1 atm

What is standard pressure in kiloPascals (kPa)?

101.3 kPa

What is standard pressure in millimeters of mercury (mmHg)?

760 mmHg

What is standard pressure in Torr (torr)?

760 torr

Which two measures of pressure are equivalent?

torr and mmHg

Why must you use Kelvin in all gas law equations?

so that you never have to divide by 0

How do you convert from Celsius to Kelvin?

C + 273 = K

What does STP stand for?

standard temperature and pressure

What is the relationship between pressure and volume?

inverse (as pressure increases, volume decreases)

What is the relationship between temperature and volume?

direct (as temperature increases, volume also increases)

What is the relationship between pressure and temperature?

direct (as pressure increases, temperature also increases)

What law deals with pressure and volume?

Boyle’s Law

What law deals with volume and temperature?

Charles’s Law

What law deals with pressure and temperature?

Gay-Lussac’s Law

What is the equation for Boyle’s Law?

P₁V₁ = P₂V₂

What is the equation for Charles’s Law?

V₁/T₁ = V_2/T₂

What is the equation for Gay-Lussac’s Law?

P₁/T₁ = P_2/T₂

What is the combined gas law made of?

all the equations of the smaller gas laws (Charles’s, Boyle’s, Gay-Lussac’s)

What is the combined gas law equation?

(P₁V₁)/T₁ = (P₂V₂)_/T₂

What can you do in the combined gas law equation if a variable is held constant?

remove it from the equation

Regardless of the identity of the gas, a mole of gas will occupy ____ of volume.

22.4 L

What is Dalton’s Law of Partial Pressure?

because the volume of a gas does not depend on identity, neither will the pressure

In a container of unreacting gases, the total pressure is equal to the sum of the pressures of the individual gases

What is the equation of Avogadro’s Law?

V₁/N₁ = V_2/N₂

^{V= volume, N=number of moles}

What is the molar volume of a gas?

22.4 L

What is the equation of the ideal gas law?

pv=nRT

^{p=pressure, v=volume, n=number of moles, R= gas constant, T=temperature}

What unit does pressure need to be in in the ideal gas law?

atmospheres (atm)

What unit does volume need to be in in the ideal gas law?

liters (L)

What unit does temperature need to be in in the ideal gas law?

Kelvin

What is the gas constant (R)?

.08206 L(atm)/mol(K)

Stoichiometry

the relationship between the quantities of reactants and products before, during, and after chemical reactions

When working with gases, what do coefficients represent in chemical equations?

moles or liters

What does 1 mol of gas always equal when at STP?

22.4 L

When is the only time you can use 1 mol=22.4 L?

when it’s a gas and when it’s at STP

What are the steps of gas stoichiometry?

1. determine and balance the equation

2. change the given to moles. For gases, you will do this using the ideal gas law. Solve for n

3. Compare two substances using a mole ratio

4. Convert the moles back to what is asked. This can be grams, moles, liters, or even molecules. For liters, use the ideal gas law and solve for V

What is the strength that liquid molecules push against the atmosphere with called?

Vapor pressure

What happens when liquids have enough every to evaporate?

they have to push against the atmosphere

How is vapor pressure typically defined?

When the lid is on a container, the liquid inside tries to evaporate. There is gas, the “empty” space on top of the liquid.

Why does temperature increase as vapor pressure increases?

because particles have more energy

What does high vapor pressure indicate?

very willing to become a gas, low boiling point, weak IMFs

What does low vapor pressure indicate?

not very willing to become a gas, high boiling point, strong IMFs

What is boiling point?

when atmospheric pressure = vapor pressure

What is the relationship between boiling point and temperature?

you can boil a substance at any temperature by adjusting the pressure

What is normal boiling point?

temperature where a substance boils at. Boiling under normal conditions (water = 100°C)

Are boiling point and normal boiling point the same?

No

Collision Theory

describes what is needed for a chemical reaction to take place; Particles must collide with proper energy and correct orientation

What two things are necessary for a chemical reaction to take place with collisions?

1. proper energy

2. correct orientation

What is it called when you have proper energy and correct orientation in a collision?

an effective collision

How do you ensure effective collisions?

• reactants will only react if their chemistry allows them to

• increase the temperature

• increase concentration

• increase surface area (solids only)

• increase pressure (for gases)

• Introduce a catalyst

How does increasing temperature help ensure effective collisions?

molecules move faster and energy increases

How does increasing concentration help ensure effective collisions?

there are more molecules in a system

How does increasing surface area help ensure effective collisions?

allows more molecules to be a part of the reaction, unshielded by other molecules

For what phase of matter can you increase surface area to create more effective collisions?

solids only

How does increasing pressure help ensure effective collisions?

keeps the gas dissolved and able to react

For what phase of matter can you increase pressure to ensure effective collisions?

gases only

How does introducing a catalyst help ensure effective collisions?

provides an “alternative reaction pathway” (shortcut) for the reaction (speeds it up)