Question

At constant pressure, which of these systems do work on the surroundings? A(g) + 2B(g) — 2C(g) A(s) +B(s) — C(g) A(s) + 2B(g) —— C(g) A(g) + B(g) — 3C(g)

Answer 1

At constant pressure , that system will do work on the surroundings in which number of gases molecule will be more produced. at constant pressure when number of gaseous products formed is more than the gaseous reactant then volume of the system increases which in turns do work on the surrounding to increases its volume. W = -PAU ( negative sign indicates system looses energy and that energy is gained by surroundings) so In Acs) + Bus) → (g) and, Ag) + Bog) - 320 amount of gasedus product is more formed than reactant so system does adork on the surroundings.