We’re being asked to calculate ΔG° at 298 K for the given reactions:

We can use the following equation to solve for ** ΔG˚_{rxn}**:

$\overline{){\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{prod}}{\mathbf{-}}{\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{\mathbf{f}\mathbf{,}\mathbf{}\mathbf{react}}}$

The values for **ΔG˚ _{f}** can be looked up in textbooks or online:

Note that we need to *multiply each ΔG˚ _{f} by the stoichiometric coefficient* since ΔG˚

Calculate ΔG° at 298 K for the following reactions.

Part A

NH_{3}(g) + HBr(g) → NH_{4}Br(s)

Part B

2 KClO_{3}(s) → 2 KCl(s) + 3 O_{2(}g)

Part C

CH_{4}(g) + 3 Cl_{2}(g → CHCl_{3}(g) + 3 HCl(g)

ΔG°_{f} for CHCl_{3}(g) is - 70.4 kJ/mol

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