Question. For each of the reactions at constant pressure, determine whether the system does work on the surroundings, the surroundings does work on the system, or essentially no work is performed.
(a) 4Fe + 3O2 –> 2Fe2O3
(b) 2H2O2 –> O2 + 2H2O
(a) For ( displaystyle4Fe(8) + 3O_2(g) → 2Fe_2O_3(8) )
Here, 3 moles of gas produce 0 moles of gas. This means that work is done on the system.
(b) And the production of a gas that occurs in a reaction is the amount of work done by more systems.
For ( displaystyle2H_2O_2(g) → O_2(g) + 2H_20(g) )
Here 2 moles of gas produce 3 moles of gas. Since the gas increases too much, work is done by the system.