# Question #20ae1

Apr 24, 2015

To answer any $\Delta {\left(X\right)}_{r x n}$ problem; where $X = {H}^{0} , {S}^{0} , \mathmr{and} {G}^{0}$ we can always use Hess's Law.

Hess's Law:
$\Delta {\left({G}^{0}\right)}_{r x n} = \left(S u m \Delta G \left(P r o \mathrm{du} c t s\right)\right) - \left(S u m \Delta G \left(R e a c \tan t s\right)\right)$

For our reaction $2 C O \left(g\right) + {O}_{2} \left(g\right) \to 2 C {O}_{2} \left(g\right)$

Notice: You cannot omit the physical state for these problems, this is why I added the (g) and I'm going to assume (g) for all.

$\Delta {\left({G}^{0}\right)}_{r x n} = \left[\left(2 m o l C {O}_{2} g \cdot - 394.4 \frac{k J}{m o l}\right)\right] - \left[\left(2 m o l C O g \cdot - 137.3 \frac{k J}{m o l}\right) + \left(1 m o l {O}_{2} g \cdot 0 \frac{k J}{m o l}\right)\right]$

Notice: the mol units cancel out leaving our answer in kJ.

$\Delta {\left({G}^{0}\right)}_{r x n} = \left[- 788.8 k J\right] - \left[- 274.6 k J\right]$

$\Delta {\left({G}^{0}\right)}_{r x n} = - 514.2 k J$