Chemistry - Thermodynamics - I Question with Solution | TestHub
A cylindrical container of volume 89.6 L is containing equal number of moles of an ideal monoatomic gas in two sections A and B, separated by an adiabatic frictionless piston as shown in the figure. The initial temperature and pressure of gas in both sections is 54.6 K and 2 atm. Now, gas in section A is slowly heated till the volume of section B becomes one-eighth of its initial volume.
The change in enthalpy of gas in Section A is
Options:
Answer:
Solution:
ΔHA = n·Cp·ΔT = 20 × (5/2 × 2 cal/K-mol) × (3274 − 54.6) = 20 × 5 × 3219.4 cal ≈ 321,940 cal ≈ 321.9 kcal. Traps: (c) results from using 10 mol instead of the 20 mol actually present in section A, and (a) from 5 mol; Cp (not Cv) must be used for enthalpy, and the full ΔT of section A (not of B, whose final temperature is only 218.4 K) must be taken. Matches (b).
