Question

Calculate the final temperature, in degrees Celsius, for each of the following, if n and V are constant. A. A sample of xenon gas at 31 ∘C and 800. mmHg is cooled to give a pressure of 560. mmHg . B. A tank of argon gas with a pressure of 0.940 atm at -14 ∘C is heated to give a pressure of 1450 torr .

Answer 1

Part a

Temperature T1 = 31 + 273 = 304 K

Pressure P1 = 800 mmHg

Temperature T2 =?

Pressure P2 = 560 mmHg

From the ideal gas equation at constant n and V

P1/P2 = T1/T2

T2 = T1 x P2 / P1

= 304 x (560/800)

= 212.8

T2 = 212.8 - 273

T2 = - 60.2 °C

Part b

Pressure P1 = 0.940 atm

Temperature T1 = - 14 + 273 = 259 K

Pressure P2 = 1450 torr x 1 atm/760 Torr

= 1.908 atm

From the ideal gas equation at constant n and V

P1/P2 = T1/T2

T2 = T1 x P2 / P1

= 259 x (1.908/0.940)

= 525.71 K

T2 = 525.71 - 273 = 252.71 °C