Molarity & Gases (Set 1)

A sample of a gas has a volume of 852 mL at 298 K. What temperature (K) is necessary for the gas to have a volume of 945 mL?

• 57.5 °C

• 57.5 °K

• 330.5 K

• 330.5°C

This graph is an example of two variables that are:

• directly proportional
• inversely proportional
• stupid
• smell funny

The partial pressures of CH₄, N₂, and O₂ in a sample of gas were found to be 135 mm Hg, 508 mm Hg, and 571 mm Hg, respectively. Calculate the mole fraction of nitrogen.

• 20.4

• 0.470

• 0.418

• 0.751

A gas sample with a mass of 12.8 g exerts a pressure of 1.2 atm at 15°C and a volume of 3.94 L. What is the molar mass of the gas?

• 19 g/mol

• 32 g/mol

• 64 g/mol

• 128 g/mol

Hydrogen gas is collected over water at 20.0^oC (and vapor pressure of 18 torr). The volume of the mixture is 1.7 L and its total pressure is 615.6 torr. How many moles of hydrogen gas are collected?

• 22.4 mol

• 0.082 mol

• 0.066 mol

• 0.056 mol

If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?

• 9 L

• .69 L

• 1.44 L

A gas is heated from 263K to 298K. The volume is increased from 24.0L to 35.0L. If the original pressure was 1.00 atm, what is the new pressure?

• 0.78 atm

• 1.65 atm

• 1.28 atm

• 0.61 atm

A 2.0 L sample of pure oxygen gas (O₂) is measured at STP. How many moles of oxygen is this?

• 42.8 mol

• 0.0077 mol

• 1.44 mol

• 0.089 mol

Calculate the volume that a 0.323-mol sample of a gas will occupy at -8^oC and a pressure of 0.900 atm.

• 7.18 L 
• 7.81 L
• 4.63 L
• 4.36 L

Aluminium reacts with hydrochloric acid [HCl (aq)] to form hydrogen gas and aluminum chloride . How many grams of aluminum are necessary to produce 11.2 L of hydrogen gas at STP?

2Al + 3H₂SO₄ -> Al₂(SO₄)₃ + 3H₂

• 9.00

• 14.2

• 27.0

• 56.4