Thermodynamics Question 371

Question: The specific heat of hydrogen gas at constant pressure is CP=3.4×103cal/kgoC and at constant volume is CV=2.4×103cal/kgoC. If one kilogram hydrogen gas is heated from 10oC to 20oC at constant pressure, the external work done on the gas to maintain it at constant pressure is

Options:

A) 105 cal

B) 104 cal

C) 103 cal

D) 5×103 cal

Show Answer

Answer:

Correct Answer: B

Solution:

[b] From FLOT DQ = DU + DW Work done at constant pressure ΔWP=ΔQPΔU ΔQPΔQV

(As we know ΔQV=ΔU )

Also ΔQP=mcPΔT

and ΔQV=mcVΔT

Therefore ΔWP=m(cPcV)ΔT

Therefore ΔWP=1×(3.4×1032.4×103)×10=104cal



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