Question

Consider a reaction that has a positive ΔH and a positive ΔS. Which of the following statements is TRUE?A) This reaction will be spontaneous only at high temperatures.B) This reaction will be spontaneous at all temperatures.C) This reaction will be nonspontaneous at all temperatures.D) This reaction will be nonspontaneous only at high temperatures.E) It is not possible to determine without more information.

Answer 1

Answer: A) This reaction will be spontaneous only at high temperatures

Explanation:

$\Delta G$= +ve, reaction is non spontaneous

$\Delta G$= -ve, reaction is spontaneous

$\Delta G$= 0, reaction is in equilibrium

Using Gibbs Helmholtz equation:

$\Delta G=\Delta H-T\Delta S$

Given : $\Delta H=+ve$

$\Delta S=+ve$

$\Delta G=(+ve)-T(+ve)$

$\Delta G=(+ve)(-ve)$

Thus the value of  $\Delta G$  is negative and spontaneous when temperature is high.