Question

Which set of the conditions given below guarantees that a reaction will be spontaneous?

• A. $\Delta H(+)$ and $\Delta S(-)$
• B. $\Delta H(-)$ and $\Delta S(+)$
• C. $\Delta H(+)$ and $\Delta S(+)$ at low temperature
• D. $\Delta H(-)$ and $\Delta S(-)$ at high temperature
• E. $\Delta G(+)$

Answer 1

The correct option is B $\Delta H(-)$ and $\Delta S(+)$

For a spontaneous reaction, $\Delta G<0$
Also, $\Delta G=\Delta H-T\Delta S$
Hence, when $\Delta H<0$ and $\Delta S>0$, $\Delta G<0$, and the reaction will become spontaneous.