Question

A process is carried out at constant pressure. Given that ΔE is positive and ΔH is negative,
Select one:
A. the system absorbs heat and contracts during the process.
B. the system absorbs heat and expands during the process.
C. the system loses heat and contracts during the process.
D. the system loses heat and expands during the process.

Answer 1

dE = q+w = dH-p(V2-V1)
If dE is + and dH is -, then w MUST be + so -p(V2-V1) must be +
With dH is - then heat must be released. That means A and B can't be right. The answer must be C or D. To make -p(V2-V1) +, must V2 or V1 be the larger number? If V2>V1, the w is -. If V2<V1, then w is +. So does the system expand or contract?