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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Luffyx10 on December 03, 2024, 11:42:28 AM

Title: Thermodynamics
Post by: Luffyx10 on December 03, 2024, 11:42:28 AM

I don’t understand why we use CV here rather than CP to get the answer.

mixture of hydrogen gas and the standard composition of air at 25°C with a total pressure of 1 atm, is exploded in a closed rigid vessel. If the combustion occurs in an adiabatic system, given that:

(i) CV (N2) = 8.3 calK−1mol−1

(ii) CP (H2O)= 11.3 calK−1mol−1

(iii)ΔH H2O(g)= -57.8 Kcal (Take air as 80% N2 , 20% O2 by volume)

What will be the maximum temperature attained if the process occurs in adiabatic container.

(A) 2940 K

(C) 1900 K

(B) 2665 K

(D) 298 K

As ΔrH is given shouldn’t I use CP rather than CV

Title: Re: Thermodynamics
Post by: Borek on December 03, 2024, 05:20:19 PM

Quote from: Luffyx10 on December 03, 2024, 11:42:28 AM

exploded in a closed rigid vessel

Sounds like Cv, no?

Title: Re: Thermodynamics
Post by: Luffyx10 on December 03, 2024, 10:20:18 PM

But don’t we always use Cp with enthalpy , that’s what I am confused at.