Project ForgeProcess Calculations
Laws of Thermodynamics
GATE 2020
Hard
One mole of ideal gas changes state from L(100kPa, 0.02 m³/mol) to N(200kPa, 0.03 m³/mol) via: Process I, a single straight-line step L→N; Process II, two steps L→M(100kPa,0.03m³/mol)→N. All steps reversible. If QI, QII are net heat into the system for each process, QI−QII (J) is
500 J(± 20 accepted)
Explanation
ΔU is the same for both paths (same end states), so QI−QII=WI−WII (work done by the system). WI=trapezoidal area under the straight line=0.5×(100+200)×(0.03−0.02)=1500 J. WII=W(L→M)+W(M→N)=100×0.01+0=1000 J (M→N is constant volume, zero work). QI−QII=1500−1000=500 J.
Source: GATE CH 2020 (2020)
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