Gas Law Review Problems
immHg
L iTorr
L ikPa
L iatm
R = 62.36 Lmol
= 62.36
= 8.314
= 0.0821
iK
mol iK
mol iK
mol iK
1. What is the volume occupied by 0.128 mol of He gas at a pressure of 0.97 atm
and 325 K?
2. If the volume of a container of gas doubles in volume while the temperature
stays constant what changes? (Be specific regarding magnitude)
3. A gas mixture contains each of the following gases at the indicated partial
pressures: N2 = 315 torr; O2 = 124 torr; and He, 219 torr. What is the total
pressure of the mixture and how many moles of oxygen would be present in
a 2.15 L sample of this mixture at 25.0°C?
4. Determine the final pressure of 12.5 L container of CO2 initially at 1.35 atm
that is compressed down to 10.3 L.
5. What is the pressure, in atm, within a 15.0 L cylinder filled with 0.448 mol of
N2 gas at a temperature of 305 K?
6. If half the moles of gas are removed from an elastic balloon what happens to
the balloon?
7. A gas mixture contains 1.25 mol of N2, 0.85 mol of O2 in a 1.55 L container at
18°C. Calculate the total pressure of the gas in atm.
8. A heliox deep-sea diving mixture contains 10.0 g of O2 (MM = 31.998 g/mol)
to every 90.0 g of He (MM = 4.0026 g/mol) at 16°C. If the pressure within the
mixture is 8.54 atm calculate the volume.
9. If the temperature within a rigid container is doubled, what changes?
10. Gas from a 3.5 L tank at STP must reach what temperature, in °C, in order to
reach 2.5 atm within a 3.0 L tank?
11. How many moles of Ne gas will occupy a 250.0 mL chamber with a pressure
of 125 kPa at 25°C?
12. Calculate the moles of H2 present in a 11.2 L chamber of gas at STP if the
partial pressure of O2 within is 0.45 atm and while H2 gas makes up the
remainder.
13. A 3.50 L tank of O2 at 1.25 atm is mixed with a 2.75 L tank of H2 at 1.50 atm.
Determine the pressure of the entire 6.25 L tank once the gases are combined
if all tanks are at 23°C.
14. Now see if you can solve number 13 using a derived gas law. (Challenge)
15. If you blow on your hand with your mouth wide the air feels ________________,
but if you narrow your lips and blow on your hand the air feels_______________.
Why?
16. A 1.0 L balloon of argon gas and a 2.2 L balloon of Cl2 gas both at STP are
compressed into a 1.5 L container. Determine the final pressure in the
container if the temperature remains constant.
Gas Law Review Solutions
1. What is the volume occupied by 0.128 mol of He gas at a pressure of 0.97 atm
and 325 K?
(0.97) V = (0.128) (0.0821) (325)
V = 3.5 L
2. If the volume of a container of gas doubles in volume while the temperature
stays constant what changes? (Be specific regarding magnitude)
The pressure inside will be half the original
3. A gas mixture contains each of the following gases at the indicated partial
pressures: N2 = 315 torr; O2 = 124 torr; and He, 219 torr. What is the total
pressure of the mixture and how many moles of oxygen would be present in
a 2.15 L sample of this mixture at 25.0°C?
315 + 124 + 219 = 658 torr = PT
(124) (2.15) = n (62.36) (298)
nO2 = 0.0143 moles
4. Determine the final pressure of 12.5 L container of CO2 initially at 1.35 atm
that is compressed down to 10.3 L.
P1V1 = P2V2  (1.35) (12.5) = P2 (10.3)  P2 = 1.64 atm
5. What is the pressure, in atm, within a 15.0 L cylinder filled with 0.448 mol of
N2 gas at a temperature of 305 K?
P (15.0) = (0.448) (0.0821) (305)  P = 0.748 atm
6. If half the moles of gas are removed from an elastic balloon what happens to
the balloon?
It will shrink to half the size
7. A gas mixture contains 1.25 mol of N2, 0.85 mol of O2 in a 1.55 L container at
18°C. Calculate the total pressure of the gas in atm.
1.25 + 0.85 = 2.10 moles of gas total
P (1.55) = 2.10 (0.0821) (291)
PT = 32.4 atm
8. A heliox deep-sea diving mixture contains 10.0 g of O2 (MM = 31.998 g/mol)
to every 90.0 g of He (MM = 4.0026 g/mol) at 16°C. If the pressure within the
mixture is 8.54 atm calculate the volume.
10.0 / 31.990 = 0.313 mol O2
90.0 / 4.0026 = 22.5 mol He
0.313 + 22.5 = 23.4 total moles
(8.45) V = (22.8) (0.0821) (289) 
V = 64.0 L
9. If the temperature within a rigid container is doubled, what changes?
The pressure doubles
10. Gas from a 3.5 L tank at STP must reach what temperature, in °C, in order to
reach 2.5 atm within a 3.0 L tank?
P1V1 P2V2
(1.0)(3.5) (2.5)(3.0)

 585 K  312°C
=
=
T1
T2
(273)
T2
11. How many moles of Ne gas will occupy a 250.0 mL chamber with a pressure
of 125 kPa at 25°C?
(125) (0.25000) = n (8.314) (298)
n = 0.0126 moles of Ne
12. Calculate the moles of H2 present in a 11.2 L chamber of gas at STP if the
partial pressure of O2 within is 0.45 atm and while H2 gas makes up the
remainder.
1.0 – 0.45 = 0.55 atm = PH2
(0.55) (11.2) = n (0.0821) (273) nH2 = 0.27 moles
13. A 3.50 L tank of O2 at 1.25 atm is mixed with a 2.75 L tank of H2 at 1.50 atm.
Determine the pressure of the entire 6.25 L tank once the gases are combined
if all tanks are at 23°C.
Tank O2

(1.25) (3.50) = n (0.0821) (296) 
nO2 = 0.180 mol O2
Tank H2

(1.50) (2.75) = n (0.0821) (296) 
nO2 = 0.170 mol H2
0.18 + 0.17 = 0.35 moles gas in the final tank
P(6.25) = (0.35) (0.0821) (296)
P = 1.36 atm
14. Now see if you can solve number 13 using a derived gas law. (Challenge)
P1V1 = P2V2
(1.25) (3.5) = P (6.25) = PO2 = 0.70 atm
(1.50) (2.75) = P(6.25) = PH2 = 0.66 atm
0.70 + 0.66 = 1.36 atm = PT
15. If you blow on your hand with your mouth wide the air feels ________________,
but if you narrow your lips and blow on your hand the air feels_______________.
Why?
Will discuss
16. A 1.0 L balloon of argon gas and a 2.2 L balloon of Cl2 gas both at STP are
compressed into a 1.5 L container. Determine the final pressure in the
container if the temperature remains constant.
Tank Ar

(1.00) (1.0) = n (0.0821) (273)

nAr = 0.045 mol Ar
Tank Cl2

(1.00) (2.2) = n (0.0821) (273)

nCl2 = 0.098 mol Cl2
0.045 + 0.067 = 0.143 moles gas in the final tank
P(1.5) = (0.143) (0.0821) (273)

P = 2.1 atm
Or
P1V1 = P2V2
(1.0)(1.0) = PAr (1.5)
PAr = 0.67 atm
(1.0) (2.2) = PCl2 (1.5)
PCl2 = 1.5 atm
0.67 + 1.5 = 2.1 atm = PT