Question

Which of the following circumstances will result in a reaction that is spontaneous at all temperatures?

positive enthalpy change and positive entropy change
negative enthalpy change and negative entropy
change positive enthalpy change and negative entropy change
negative enthalpy change and positive entropy change

Answer 1

negative enthalpy change and positive entropy change. I am sure that's the answer!

Answer 2

Answer: negative enthalpy change and positive entropy change

Explanation:-

According to Gibb's equation:

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

`\Delta G` = Gibbs free energy

`\Delta H` = enthalpy change

`\Delta S` = entropy change

T = temperature in Kelvin

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

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

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

Thus when
`\Delta H` = -ve

`\Delta S` = +ve

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

`\Delta G=(-ve)(-ve)=-ve`

Reaction is spontaneous at all temperatures.