A sample of carbon dioxide gas at a pressure of 686 mm Hg and a temperature of 73 C, occupies a volume of 6.34 liters. If the gas is cooled at constant pressure to a temperature of 35 C, the volume of the gas sample will be L.

Recall the ideal gas law,

P V = n R T

Find the amount of CO₂ in the sample, n :

P = 686 mm Hg ≈ 91,459 Pa

V = 6.34 L

R = 8.3145 J/(mol•°K)

T = 73 °C = 346.2 °K

→   n = P V / (R T ) ≈ 0.20147 mol

Now find the volume V of the sample when the temperature T is 35 °C = 308.2 °K :

V = n R T / P ≈ 5.6349 L ≈ 5.63 L