Chemistry Test Gas Laws 4

Question 1

Using PV = nRT, what is the pressure of 0.5 mol of gas in a 10.0 L container at 300 K? (R = 0.0821 L·atm/mol·K)

Accepted Answer

1.23 atm

Answer

P = nRT/V = (0.5)(0.0821)(300)/10.0 = 1.23 atm.

Question 2

Graham's Law of Effusion states that the rate of effusion is inversely proportional to which property?

Accepted Answer

Square root of molar mass

Answer

Graham's Law: rate ∝ 1/√M, so heavier gases effuse more slowly.

Question 3

Which gas effuses faster: H2 (M = 2 g/mol) or O2 (M = 32 g/mol), and by what factor?

Accepted Answer

H2, by a factor of 4

Answer

Rate ratio = √(32/2) = √16 = 4, so H2 effuses 4 times faster than O2.

Question 4

A real gas deviates most from ideal behavior under which conditions?

Accepted Answer

Low temperature and high pressure

Answer

At low temperature and high pressure, intermolecular forces and molecular volume become significant, causing deviation from ideal behavior.

Question 5

What is the mole fraction of N2 in a mixture where N2 has a partial pressure of 0.8 atm and total pressure is 2.0 atm?

Accepted Answer

0.4

Answer

Mole fraction = partial pressure / total pressure = 0.8/2.0 = 0.4.

Chemistry Practice Test