First slide
Different type of processes

4.0 g  of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0JK-1 mol-1. If the speed of sound in this gas at NTP is 952 ms-1, then the heat capacity at constant pressure is

(Take gas constant R = 8.3 JK-1mol-1)


Since 4.0g of a gas occupies 22.4 litres at NTP, so the molecular mass of the gas is
M=4.0 g mol-1
As the speed of the sound in the gas is


where γ is the ratio of two specific heats, R is the universal gas constant and T is the temperature of the gas.


 Here, M=4.0 g mol-1=4.0×10-3 kg mol-1

v=952 ms-1,R=8.3JK-1 mol-1 and T=273 K (at NTP) 

  γ=4.0×10-3 kg mol-1952 ms-128.3JK-1 mol-1(273 K)=1.6

By definition, 

γ=CpCv   or   Cp=γCv

 But γ=1.6 and Cv=5.0JK-1 mol-1

  Cp=(1.6)5.0JK-1 mol-1

                  =8.0JK-1 mol-1


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