Question

One mole of o2 gas is heated at constant pressure starting at 27 degree Celsius.how much energy must be added to the gas as heat to double its volume

Answer 1

one mole of O2 gas is heated at constant pressure starting from 27°C or (273 + 27) = 300K.

at constant pressure,

volume is directly proportional to temperature.

so, if volume becomes double then definitely temperature will be double of its initial value.

so, final Temperature , T = 2 × 300 = 600K

O2 is diatomic molecule so, molar heat capacity at constant pressure , Cp = 7R/2 , where R is universal gas constant.i.e., R = 25/3 J/mol.K

now, heat = nCp∆T

= 1 × 7R/2 × (600 - 300)

= 7/2 × 25/3 × 300

= 7 × 25 × 50

= 8750 J