If three moles of an ideal gas at 300 K expand isothermally from 30 dm 3 to 45 dm 3 against a constant opposing pressure of 80 kPa , then the amount of heat transferred is __________J.

Step-by-step solution

Given, V 1 = 30 dm 3 V 2 = 45 dm 3 P = 80 kPa Using, first law of thermodynamics, ΔU = Q + W Q is the heat given or lost ΔU is the change in internal energy W is the work done ΔU = 0 : Process is isothermal Q = - W W = - P ext ΔV : Irreversible W = - P ext ( V 2 - V 1 ) = - 80 × 10 3 ( 45 - 30 ) × 10 - 3 = - 1200 J Hence, the amount of heat transferred is 1200 J