Summary Week 1 Assignment

Week 4 Assignment: 20 points

Solve these ideal gas law problems. Show all work for credit.


1. A gas occupies 250 mL at 739 mmHg. For a gas at constant temperature, determine the volume
of gas at 514 mmHg. (1.5 points)
a. Answer : 359 mL
b. Work : Use Boyle’s Law
P1V1= P2V2
739mmHg x 250mL = 514mmHg*V2
V2=(739mmHg x 250mL) / 514mmHg
= 359mL




2. Use the molar volume of a gas, at STP, to determine the number of moles of CO 2 in 4.00 L of CO2
gas. (1.5 points)
a. Answer : 0.179moles
b. Work : Molar volume of gas at STP = 22.4L
22.4 L of CO2 gas = 1 mol of CO2 gas
4 L of CO2 gas = 4L of CO2 x 1mol of CO2 gas/22.4L of CO2 gas = 0.179 moles

3. A sample of nitrogen (N2) has a volume of 50.0 L at a pressure of 2 ATM. What is the volume of
gas at a pressure of 15 atm, if there is no change in temperature? (1.5 points)
a. Answer : 6.67L
b. Work : P1V1= P2V2
2 atm x 50L = 15atm x V2
V2=(2 atm x 50L)/15 atm = 6.67L

4. A 0.6 L canister of Oxygen gas has a temperature of 297 K contains 21 mols of O 2 gas. What is
the pressure of this tank? (1.5 points)
a. Answer :
b. Work :PV =nRT
P = nRT/V ; R = gas constant = 0.0821L atm K-1 mol-1
T=297K
V=0.6L
P=(21moles x 0.0821L atm K-1 mol-1 x 297K)/0.6L
P=853.4atm

5. Calculate the pressure, in atmospheres, of 8.67 mol CO(g) in a 2.0 L tank at 48 degrees C. (1
points)
a. Answer : 114.0 atm
b. Work : P = nRT/V
T = 48oC = 48 + 273