One mole of ideal monoatomic gas is mixed with four moles of diatomic gas. What is γ for the mixture? (γ denotes the ratio of specific heat at constant pressure, to that at constant volume)

Answer 1

C_V(monatomic) = 3/2 R and C_V(diatomic) = 5/2 R

The C_V combine as a mole weighted average: C_V(mix) = .2(3/2 R) + .8(5/2 R)

C_P(mix) = C_V(mix) + R

γ = C_P/C_V