Question

The chemical reaction that causes iron to corrode in air is given by

Answer 1

Answer :

(A) The value of $\Delta G^o$ at 298 K is, 1521.9 kJ

(B) The value of $\Delta G^o$ at 3652 K is, -301.59 kJ

Explanation :

Part A :

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

where,

$\Delta G^o$ = standard Gibbs free energy  = ?

$\Delta H^o$ = standard enthalpy = 1684 kJ = 1684000 J

$\Delta S^o$ = standard entropy = 543.7 J/K

T = temperature of reaction = $298K$

Now put all the given values in the above formula, we get:

$\Delta G^o=(1684000J)-(298K\times 543.7J/K)$

$\Delta G^o=1521977.4J=1521.9kJ$

Part B :

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

where,

$\Delta G^o$ = standard Gibbs free energy  = ?

$\Delta H^o$ = standard enthalpy = 1684 kJ = 1684000 J

$\Delta S^o$ = standard entropy = 543.7 J/K

T = temperature of reaction = $3652K$

Now put all the given values in the above formula, we get:

$\Delta G^o=(1684000J)-(3652K\times 543.7J/K)$

$\Delta G^o=-301592.4J=-301.59kJ$