Chem Notes Ch 6

Question 1

Temperature

Answer 1

Unit is Kelvins or centigrade.

1K = 1C + 273

Question 2

Volume

Answer 2

Unit is liters.

1L = 1000mL = 1000 𝑐𝑚^3

Question 3

Pressure

Answer 3

Equal to force divided by area. Caused by contact between gas molecules and their
container. Most common unit used for pressure on the DAT is atmosphere.
1atm = 760 torr = 760 mmHg

Question 4

Behaviours of an ideal gas

Answer 4

1. Gas molecules themselves take up no volume. They are essentially point particles that have no volume in and of themselves.
2. Gas molecules collide with each other elastically, which means the intermolecular forces involved are negligible.
3. All collisions are elastic = no intermolecular forces = no loss of kinetic energy.
4. The average kinetic energy of a gas depends on the system’s temperature.

Gases behave MOST ideally at low pressures and high temperatures.

Question 5

Ideal gas law

Answer 5

Pressure and volume are inversely proportional. Volume and temperature are directly proportional. Pressure and temperature are directly proportional.

PV = nRT

P = Pressure
V = Volume
T = Temperature (MUST be in Kelvins!) 
n = Number of moles
R = Constant equal to 0.0821 L∙atm/mol∙K

Question 6

STP

Answer 6

1 mole of gas at STP (P = 1 atm, T = 273K) is 22.4 L.

Question 7

Boyle’s Law

Answer 7

Pressure and volume are inversely proportional under constant temperature

Question 8

Charles’ Law

Answer 8

Volume and temperature are directly proportional under constant pressure

Question 9

Avogadro’s Law

Answer 9

Volume and number of moles are directly proportional.

Equal volumes of all gasses at the same temperature and pressure have the same number of molecules.

Question 10

Dalton’s Law of Partial Pressure

Answer 10

In a mixture of gases, the total pressure of the mixture is equal to the summation of partial pressures of individual gases: Ptotal = P1 +P2 +P3 +…

The partial pressure of each gas can be calculated from the product of the total pressure and the mole fraction of the gas: P1 = (𝒳)*(Ptotal)

Question 11

Graham’s Law of Effusion

Answer 11

Rate of effusion of a gas is inversely proportional to the square root of its molar mass.

(rate of effusion of gas #1/rate of effusion of gas #2) = sqrt (molar mass of gas #2/molar mass of gas #1)

The gas that has the lowest molar mass has the highest rate of effusion

Question 12

Gas density

Answer 12

Density = [(P)(Molar Mass)]/ [(R)(T)]

The heaviest gas has the highest density