Question

For the reactions, $N_2\left(g\right)+3H_2\left(g\right)⟶2N{H}_3\left(g\right)$ predict, whether the work is done on the system or by the system?

• A. Done by the system
• B. Done on the system
• C. Cannot be determined
• D. None of the above

Answer 1

The correct option is B Done on the system

Number of moles of gaseous reactants = 4
Number of moles of gaseous products = 2
As the reaction proceeds, there is decrease in the number of moles of gaseous species. Volume is directly proportional to the number of moles. Hence, volume decreases. Decrease in the volume indicates that work is done on the system.