Chemistry - Thermochemistry Question with Solution | TestHub
An intimate mixture of hydrogen gas and the theoretical amount of air at 25°C and a total pressure of 1 atm, is exposed in a closed rigid vessel. If the process occurs under adiabatic condition, then using the following data, answer the following questions:
Given: (i) CP,m = 8.3 cal/K-mol (ii) CP,m = 11.3 cal/K-mol (iii) Δf H [H2O(g)] = -57.8 kcal (iv) Air contains 20% O2 and 80% N2 by volume
What will be the final pressure (approximately)?
Options:
Answer:
Solution:
At constant volume, pressure P is proportional to the product of the number of moles n and temperature T, i.e., P ∝ nT.
Therefore, the final pressure Pf can be calculated as:
Pf = Pi × nfTf/niTi
Given Pi = 1 atm, nf = 6 mol, Tf = 2940 K, ni = 7 mol, and Ti = 298 K:
Pf = 1 atm × (6 mol × 2940 K)/(7 mol × 298 K) = 8.46 atm ≈ 8.5 atm
This corresponds to option (a).
