Question

A substance $X{Y}_3$ decomposes as :
The ratio of partial pressure of $XY$ and $X{Y}_2$ in the mixture of gases obtained by decomposition of $X{Y}_3$ (g) is 2 : 1. Find the total enthalpy change for the decomposition of 1 mole of $X{Y}_3$.

• A. 53.33 kJ/mol
• B. 160 kJ/mol
• C. 110 kJ/mol
• D. 1110.33 kJ/mol

Answer 1

The correct option is A 53.33 kJ/mol

If we have 3 moles of $X{Y}_3$, to begin with, then we end up with 2 moles of $XY$ and 1 mole of $X{Y}_2$ on its decomposition.
Then,
Total enthalpy change of decomposition of 3 mole $X{Y}_3=2\times 50+1\times 60=160kJ$.
Hence, enthalpy change for 1 mole of $X{Y}_3=\frac{160kJ}{3}$