Thermochemistry, calculating T given Q
We know that, at temperature T, $$\Delta G^0(T)=\Delta H^0(T)-T\Delta S^0(T)$$
From Hess's Law, we also know that 
$$\Delta H^0(T)=\Delta H^0(298)+???$$
and
$$\Delta S^0(T)=\Delta S^0(298)+???$$

That should be a good enough hint.