Question

For the gas - phase decomposition, ${PCl}_5\left(g\right)\underset{\rightleftharpoons }{\Delta }{PCl}_3\left(g\right)+{Cl}_2\left(g\right)$:-

• A. $\Delta H<0,\Delta S<0$
• B. $\Delta H>0,\Delta S>0$
• C. $\Delta H>0,\Delta S<0$
• D. $\Delta H<0,\Delta S>0$

Answer 1

Answer: (B)

$\Delta H>0,\Delta S>0$

In this process:

${PCl}_5\left(g\right)\underset{\rightleftharpoons }{\Delta }{PCl}_3\left(g\right)+{Cl}_2\left(g\right)$

as no of product are more so entropy increases.

similarly enthalpy of system increases because of higher no of products.