Question #44239

Consider the following sequential reactions for the synthesis of a solid material $\ce{D(s)}$ from gaseous precursors $\ce{A(g)}$ and $\ce{B(g)}$:

Step 1: $\ce{A(g) + B(g) \rightleftharpoons C(g)}$ Step 2: $\ce{C(g) \rightleftharpoons D(s)}$

The standard thermodynamic parameters ($\Delta H_f^\circ$ in $\text{kJ mol}^{-1}$, $S^\circ$ in $\text{J K}^{-1} \text{ mol}^{-1}$) at $298 \text{ K}$ are given as follows: $\ce{A(g)}$ ($50$, $200$); $\ce{B(g)}$ ($50$, $200$); $\ce{C(g)}$ ($-40$, $200$); $\ce{D(s)}$ ($-140$, $100$).

Assuming these values are independent of temperature, identify the crossover temperature ($T_{eq}$) for the overall net reaction, and the value of the net standard Gibbs free energy change ($\Delta G^\circ_{net}$) at $750 \text{ K}$.