Question

Zinc reacts with dilute hydrochloric acid to give hydrogen at `17^(@)C`. The enthalpy of the reaction is `-12.55kJ` `mol^(-1)` of zinc and entropy change equals 5.0 J `k^(-1)" "mol^(-1)` for the reaction. Calculate the free energy change and predict whether the reaction is spontaneous or not.

Answer 1

Given, `DeltaH=-12.55kJ" "mol^(-1)`
`DeltaS=5.0J" "K^(-1)" "mol^(-1)`
`=0.005kJ" "K^(-1)" "mol^(-1)`
`T=17+273=290K`
Applying `DeltaG=DeltaH-TDeltaS`
`=12.55-0.005xx290`
`=-12.55-1.45=-14.00kJ" "mol^(-1)`
Since, `DeltaG` is negative, the reaction will be spontaneous.