We’re being asked to determine the Gibbs free energy (ΔG°_{rxn}) at 25°C for the given reaction:
2 KClO_{3 }(s) → 2 KCl (s) + 3 O_{2 }(g)
We’re given the ΔH˚_{f} and S˚ of each reactant and product:
Substance | ΔH˚_{f} (kJ/mol) | S˚ (J/mol • K) |
KClO_{3 }(s) | –397.7 | 143.1 |
KCl (s) | –436.5 | 82.6 |
O_{2 }(g) | 0 | 205.2 |
We can use the following equation to solve for ΔG˚_{rxn}:
$\overline{){\mathbf{\Delta G}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{=}}{\mathbf{\Delta H}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}{\mathbf{-}}{\mathbf{T\Delta S}}{{\mathbf{\xb0}}}_{{\mathbf{rxn}}}}$
For this problem, we need to do the following steps:
Step 1: Calculate ΔH˚_{rxn}.
Step 2: Calculate ΔS˚_{rxn}.
Step 3: Use ΔH˚_{rxn} and ΔS˚_{rxn} to calculate for ΔG˚_{rxn}.
For the reaction:
2KClO_{3}(s) → 2KCl(s) + 3O_{2}(g)
Calculate ΔGº_{rxn} at 25ºC.
Express your answer using one decimal place.
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What scientific concept do you need to know in order to solve this problem?
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