3.

A gas has a volume of 225 L at 175 K and 150 kPa. What will be its volume at a temperature

of 112 K and pressure remains constant?

4

.

A gas is heated to 180 K at a constant pressure of 1 atm. If the container expands to hold a

volume of 44.8 L, what was the volume of the gas, at a temperature of 90 K?

A 200 L sample of gas is collected at 50 kPa and a temperature of 271 K. What volume

would this gas occupy at 100 kPa and a temperautre of 14 K?

6.

Find the new volumes if the values given below change to STP (273 K and 101.3 kPa) ...

(a) 24.6 L at 25°C and 10 atm

3. V = 0.2673 L

4. V = 2.4314 L

5. V = 0.262 L

6. V = 2.224 L

Explanation:

3. assuming ideal gas:

PV = RTn

∴ R = 0.082 atm. L/K. mol

∴ V1 = 225 L

∴ T1 = 175 K

∴ P1 = 150 KPa = 1.48038 atm

⇒ n = RT/PV

⇒ n = ((0.082 atm. L/K. mol) (175 K)) / ((1.48038 atm) (225 L))

⇒ n = 0.043 mol

∴ T2 = 112 K

∴ P2 = P1 = 150 KPa = 1.48038 atm

⇒ V2 = RT2n/P2

⇒ V2 = ((0.082 atm. L/K. mol) (112 K) (0.043 mol)) / (1.48038 atm)

⇒ V2 = 0.2673 L

4. gas is heated at a constant pressure

∴ T1 = 180 K

∴ P = 1 atm

∴ V1 = 44.8 L

⇒ n = RT/PV

⇒ n = ((0.082 atm. L/K. mol) (180 K)) / ((1 atm) (44.8 L))

⇒ n = 0.3295 mol

∴ T2 = 90 K

⇒ V2 = RT2n/P

⇒ V2 = ((0.082 atm. L/K. mol) (90 K) (0.3295 mol)) / (1 atm)

⇒ V2 = 2.4314 L

5. V1 = 200 L

∴ P1 = 50 KPa = 0.4935 atm

∴ T1 = 271 K

⇒ n = RT/PV

⇒ n = ((0.082 atm. L/K. mol) (271 K)) / ((0.4935 atm) (200 L))

⇒ n = 0.2251 mol

∴ P2 = 100 Kpa = 0.9869 atm

∴ T2 = 14 K

⇒ V2 = RT2n/P2

⇒ V2 = ((0.082 atm. L/K. mol) (14 K) (0.2251 mol)) / (0.9869 atm)

⇒ V2 = 0.262 L

6. a) ∴ V1 = 24.6 L

∴ P1 = 10 atm

∴ T1 = 25°C = 298 K

⇒ n = RT/PV

⇒ n = ((0.082 atm. L/K. mol) (298 K)) / ((10 atm) (24.6 L))

⇒ n = 0.0993 mol

∴ T2 = 273 K

∴ P2 = 101.3 KPa = 0.9997 atm

⇒ V2 = RT2n/P2

⇒ V2 = ((0.082 atm. L/K. mol) (273 K) (0.0993 mol)) / (0.9997 atm)

⇒ V2 = 2.224 L