Name: ________________________
Hour: ____ Date: ___________
Chemistry: Density of Gases
Solve each of the following problems, being sure to show your work and include all proper units.
1. A sample of gas has a density of 0.53 g/L at 225 K and under a pressure of 108.8 kPa. Find the density of
the gas at 345 K under a pressure of 68.3 kPa.
2. A sample of gas with a mass of 26 g occupies a volume of 392 L at 32oC and at a pressure of 0.95 atm. Find
the density of the gas at STP.
3. A gas sample has a density of 1.77 x 10–4 g/L when the temperature is 15oC and the pressure is 780 mm Hg.
Find the density of the gas at STP.
4. What is the mass of a 3.00 L sample of a gas if this volume was measured at 40 oC and 99.2 kPa? Assume
that the density of the gas at 20oC and 101.3 kPa is 1.43 g/L.
5. A sample of gas has a volume of 2.68 L when the temperature is –54oC and the pressure is 195.0 kPa. If the
density of the gas is 0.322 g/L at STP, find the mass of the sample.
Answers:
1. 0.217 g/L
2. 0.078 g/L
3. 1.82 x 10-4 g/L
4. 3.93 g
5. 2.07 g
KEY
Chemistry: Density of Gases
Solve each of the following problems, being sure to show your work and include all proper units.
1. A sample of gas has a density of 0.53 g/L at 225 K and under a pressure of 108.8 kPa. Find the density of
the gas at 345 K under a pressure of 68.3 kPa.
P1  108.8 kPa
P2  68.3 kPa
V1  ?
V2  ?
T1  225 K
T2  345 K
D1  0.53 g/L
D 2  ? g/L
P1V1
T1
=
P2 V2
T2
 1 
 1
 P2 
P1 
D
 1=
 D2

T1
1
V
D
D
or
P1
P2

D1T1 D 2 T2

T2
68.3 kPa
108 .8 kPa
=
0.53 g/L 225 K  225 K D 2 
Assume mass  1 g.




1
V
D 2  0.217 g/L
2. A sample of gas with a mass of 26 g occupies a volume of 392 L at 32oC and at a pressure of 0.95 atm. Find
the density of the gas at STP.
P1  0.95 atm
P2  1 atm
V1  392 L
V2  ? L
T1  32 C  273  305 K
T2  273 K
m  26 g
m  26 g
o
P1V1
T1
=
P2 V2
0.95 atm 392 L   1 atmV2 

T2
305 K
V2  333 L
D
273 K
26 g
m

V
333 L
D  0.078 g/L
3. A gas sample has a density of 1.77 x 10–4 g/L when the temperature is 15oC and the pressure is 780 mm Hg.
Find the density of the gas at STP.
P1  780 mm Hg
P2  760 mm Hg
V1  ?
V2  ?
T1  15 C  273  288 K
T2  273 K
D1  1.77  10
D 2  ? g/L
o
-4
g/L
P1V1
T1
=
P2 V2
T2

780 mm Hg
1.77  10
4

P1
P2

D1T1 D 2 T2
g/L 288 K 
=
760 mm Hg
D 2 273 K 
D2  1.82  104 g/L
KEY- Page 2
Chemistry: Density of Gases
4. What is the mass of a 3.00 L sample of a gas if this volume was measured at 40oC and 99.2 kPa? Assume
that the density of the gas at 20oC and 101.3 kPa is 1.43 g/L.
P1  99.2 kPa
P2  101.3 kPa
V1  3.0 L
V2  ?
T1  40 C  273  313 K
T2  20 C  273  293 K
D1  1.31 g/L
D 2  1.43 g/L
o
P1V1
o
T1
=
P2 V2

T2
P1
P2

D1T1 D 2 T2
99 .2 kPa
101.3 kPa
=
D1 313 K  1.43 g/L 293 K 
D1  3.31 g/L
Finally, calculate the mass of the gas
 1.31 g 
x g  3.0 L
  3.93 g
 1L 
5. A sample of gas has a volume of 2.68 L when the temperature is –54oC and the pressure is 195.0 kPa. If the
density of the gas is 0.322 g/L at STP, find the mass of the sample.
P1  195 kPa
P2  101.3 kPa
V1  2.68 L
V2  ?
T1  - 54 C  273  219 K
T2  273 K
D1  ? g/L
D 2  0.322 g/L
o
P1V1
T1
=
P2 V2
T2

P1
P2

D1T1 D 2 T2
195 kPa
101.3 kPa
=
D1 219 K  0.322 g/L 273 K 
D1  0.773 g/L
Finally, calculate the mass of the gas
 0.773 g 
x g  2.68 L
  2.07 g
 1L 
Answers:
1. 0.217 g/L
2. 0.078 g/L
3. 1.82 x 10-4 g/L
4. 3.93 g
5. 2.07 g