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Question : A cylinder with movable piston contain 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of a heat insulator, and the piston is insulated by having a pile of sand on it. By what factor does the pressure of the gas increase if the gas is compressed to half of its original volume? [2.639]

Doubt by Jayant

Solution : 

This is an adiabatic process.
n = 3
V1 = V
V= V/2

P2/P1 = ?

For Adiabatic Process
PVγ = constant
P1V1γ=P2V2γ

V1γ/V2γ = P2/P1
P2/P= (V1/V2)γ
P2/P1=[V/(V/2)]γ
P2/P1 = 2γ