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Question
Write the mathematical expression of the First Law of Thermodynamics for the Isobaric process.
Solution
Usually, chemical reactions are carried out in open containers under constant atmospheric pressure. In such reactions, ∆V ≠ 0
∵ ∆U = Q - Pext ∆V ...(1)
Replacing Q by Qp and ∆U by Qp - Pext ∆V in equation (1) gives
Qp = ∆U + Pext ∆V
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