General Chemistry

Question

At constant pressure, which of these systems do work on the surroundings? Check all that apply.

___ A(s) + B(s) ---> C(g)

___2A(g) + 2B(g) ---> 5C(g)

___2A (g) + 2B(g) ---> 3C(g)

___2A(g) + 3B(g) ---> 4C(g)

Answer 1

At constant pressure, the work done is equal to P∆V. Thus, the following systems do work on the surroundings:

A(s) + B(s) ---> C(g)

2A(g) + 2B(g) ---> 5C(g)

Why? Because the change in moles of gas from reactant side to product side is positive (+), meaning work is being done by the system on the surroundings.