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#gas constant

4 public questions tagged with this topic.

Cyclic Processes and Reversibility Concepts

What is the molar specific heat capacity at constant pressure for a monatomic gas if R = 8.3 J mol⁻¹ K⁻¹ ?

**Cyclic work** equals area inside loop, for rectangular cycle P₁V₁→P₂V₁→P₂V₂→P₁V₂→P₁V₁, W = (P₂-P₁)(V₂-V₁), heat absorbed and rejected during different legs, net work output for heat engine, input for refrigerator. For monatomic gas: C_v = (3)/(2) R , C_p = C_v + R . C_v = (3)/(2) × 8.3 = 12.45 . C_p = 12.45 + 8.3 = 20.75 J mol⁻¹ K⁻¹ . Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P ΔV, isothermal W = n R T ln(V₂/V₁), adiabatic P V^γ = const and η = 1 - T_c/T_h, evaluation yields 20.75 J mol⁻¹ K⁻¹, consistent

Ref: NCERT > Physics Book > Thermodynamics > Cyclic Processes and Reversibility Concepts

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First Law of Thermodynamics Applications

What is the molar specific heat capacity at constant pressure for a diatomic gas if R = 8.3 J mol⁻¹ K⁻¹ ?

**First law of thermodynamics** ΔU = Q - W, ΔU internal energy change (J), Q heat added to system (J), W work done by system (J), sign convention physics Q positive when added, W positive when done by system, energy conservation, for isochoric W=0 ΔU=Q, for adiabatic Q=0 ΔU=-W, for isothermal ΔU=0 Q=W, for cyclic ΔU=0 Q_net=W_net. For diatomic gas: C_v = (5)/(2) R , C_p = C_v + R = (7)/(2) R . C_p = (7)/(2) × 8.3 = 29.05 J mol⁻¹ K⁻¹ ≈ 29.1 J mol⁻¹ K⁻¹ . Using first law ΔU = Q - W, W = ∫ P dV, isobaric W

Ref: NCERT > Physics Book > Thermodynamics > First Law of Thermodynamics Applications

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