Find the molecular mass of a gas if its specific heats are Cₚ=0.20 cal g⁻¹ °C⁻¹ and Cᵥ=0.15 cal g⁻¹ °C⁻¹. Take R=2 cal mol⁻¹ °C⁻¹.
Physics · Thermodynamics
JEE Advanced

Question

Find the molecular mass of a gas if its specific heats are Cₚ=0.20 cal g⁻¹ °C⁻¹ and Cᵥ=0.15 cal g⁻¹ °C⁻¹. Take R=2 cal mol⁻¹ °C⁻¹.

G1 Physics · Accepted Answer

Use PV=nRT, U=(f/2)nRT, γ=1+2/f and vᵣₘₛ=√(3RT/M). At the same temperature, average translational kinetic energy depends only on T. Substituting the given values gives 40.