Question

A chemical reaction has an increase in entropy and a decrease in enthalpy. what is known about the spontaneity of the reaction? spontaneous at high temperatures, nonspontaneous at low temperatures nonspontaneous at high and low temperatures spontaneous at low temperatures, nonspontaneous at high temperatures spontaneous at high and low temperatures

Answer 1

I think the correct answer would be the first option. A chemical reaction that has an increase in entropy and a decrease in enthalpy is spontaneous at high temperatures. This reaction absorbs heat for it to occur so supplying heat to it is important. 

Answer 2

Answer: spontaneous at high and low temperatures

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

$\Delta G$ = Gibb's free energy change

$\Delta H$= enthalpy change

T = temperature

$\Delta S$ = entropy change

A reaction is spontaneous when $\Delta G$ = Gibb's free energy change is negative.

Given $\Delta H$= decrease in enthalpy = -ve

$\Delta S$ = increase in entropy = +ve

Thus $\Delta G=(-\Delta H)-T(+\Delta S)$

$\Delta G=-(\Delta H)-T(\Delta S)=-ve$

As  $\Delta G$ is always negative, it is spontaneous at all the temperatures.