Density of Gases - FREE Chemistry Materials, Lessons ...

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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 40oC 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 V1 ? T1 225 K D1 0.53 g/L

P2 68.3 kPa V2 ? T2 345 K D2 ? g/L

P1V1 = P2 V2

T 1

T 2

P1

1 D1

= P2

1 D2

T 1

T 2

P 1 D1T1

P2 D 2 T2

Assume mass 1g.

1 V or D 1

D

V

108.8 kPa = 68.3 kPa 0.53 g/L 225 K 225 K D2

D2 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 V1 392 L T1 32o C 273 m 26 g

305 K

P2 1atm V2 ? L

T2 273 K m 26 g

P1V1 = P2 V2

T 1

T 2

0.95 atm 392 L 305 K

1atm V2 273 K

V2 333 L

D m V

26 g 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 V1 ? T1 15 o C 273 288 K D1 1.77 10 -4 g/L

P2 760 mm Hg V2 ? T2 273 K D2 ? g/L

P1V1 = P2 V2

T 1

T 2

P 1 D1T1

P2 D 2 T2

780 mm Hg

= 760 mm Hg

1.77 10 4 g/L 288 K D2 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 V1 3.0 L T1 40 o C 273 313 K D1 1.31g/L

P2 101.3 kPa V2 ? T2 20o C 273 293 K D2 1.43 g/L

P1V1 = P2 V2

T 1

T 2

P 1 D1T1

P2 D 2 T2

99.2 kPa = 101.3 kPa D1 313 K 1.43 g/L 293 K

Finally, calculate the mass of the gas x g 3.0 L 1.31 g 3.93 g 1L

D1 3.31g/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.

P1 195 kPa V1 2.68 L T1 - 54 o C 273 D1 ? g/L

219 K

P2 101.3 kPa V2 ?

T2 273 K D2 0.322 g/L

P1V1 = P2 V2

T 1

T 2

P 1 D1T1

P2 D 2 T2

195 kPa = 101.3 kPa D1 219 K 0.322 g/L 273 K

Finally, calculate the mass of the gas x g 2.68 L 0.773 g 2.07 g 1L

D1 0.773 g/L

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

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