Question

Write the mathematical expression of the First Law of Thermodynamics for the Isobaric process.

Answer 1

Usually, chemical reactions are carried out in open containers under constant atmospheric pressure. In such reactions, ∆V ≠ 0

∵ ∆U = Q − P_ext ∆V   ...(1)

Replacing Q by Q_p and ∆U by Q_p − P_ext ∆V in equation (1) gives

Q_p = ∆U + P_ext ∆V