Chapter 12, Problem 49E

Without doing a numerical calculation, determine which of the following will reduce the free energy change for the reaction, that is, make it less positive or more negative, when the temperature is increased. Explain.

(a) ${\text{N}}_2\left(g\right)+3{\text{H}}_2\left(g\right)\to 2{\text{NH}}_3\left(g\right)$

(b) $\text{HCl}\left(g\right)+{\text{NH}}_3\left(g\right)\to {\text{NH}}_4\text{Cl}\left(s\right)$

(c) ${\left({\text{NH}}_4\right)}_2{\text{Cr}}_2{\text{O}}_7\left(s\right)\to {\text{Cr}}_2{\text{O}}_3\left(s\right)+4{\text{H}}_2\text{O}\left(g\right)+{\text{N}}_2\left(g\right)$

(d) $2\text{Fe}\left(s\right)+3{\text{O}}_2\left(g\right)\to {\text{Fe}}_2{\text{O}}_3\left(s\right)$