Thermodynamics

Work (Isothermal Process)

W=nRTlnVfViW = nRT\ln\frac{V_f}{V_i}

Work for isothermal (constant T) expansion of ideal gas.

Variables

W
Work
Work by gas
J
n
Moles
Amount of gas
mol
R
Gas constant
8.314
J/(mol·K)
T
Temperature
Constant temperature
K
V_f
Final volume
Final volume
V_i
Initial volume
Initial volume

Derivation

W = ∫P dV = ∫(nRT/V) dV = nRT ln(V_f/V_i).

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Common questions

What is the Work (Isothermal Process) formula?

Work (Isothermal Process) is written W = nRTlnV_f/Vᵢ. Work for isothermal (constant T) expansion of ideal gas. It belongs to Thermodynamics, under First Law.

What are the units in W = nRTlnV_f/Vᵢ?

In SI units, W is work, measured in kg·m²/s²; n is moles, measured in mol; R is gas constant, measured in kg·m²/(s²·mol·K); T is temperature, measured in K; V_f is final volume, measured in m³; V_i is initial volume, measured in m³.

How is the Work (Isothermal Process) formula derived?

W = ∫P dV = ∫(nRT/V) dV = nRT ln(V_f/V_i). The result is W = nRTlnV_f/Vᵢ.