The Standard Reaction Free Energy AG° = -194. KJ For This Reaction: SnO2(S) + 2 CO(G)—Sn(S) + 200 (9) Use This Information To Complete The Table Below. Round Each Of Your Answers To The Nearest KJ Reaction AG 2Sn(S) + 4CO2(G) 25n0, (S) + 4CO(G) OkJ KJ Sn(S) + 200,(3) — Sn0,-) + 200(3) Sn0,6) +
The Correct Answer and Explanation is :
To determine the standard Gibbs free energy changes (ΔG°) for the given reactions, we can utilize the provided ΔG° value of -194 kJ for the reaction:
SnO₂(s) + 2 CO(g) → Sn(s) + 2 CO₂(g)
1. Reaction: 2 Sn(s) + 4 CO₂(g) → 2 SnO₂(s) + 4 CO(g)
This reaction is the reverse of the original reaction, but with all coefficients multiplied by 2. Reversing a reaction changes the sign of ΔG°, and multiplying the coefficients by a factor scales ΔG° by the same factor. Therefore:
ΔG° = 2 × (+194 kJ) = +388 kJ
2. Reaction: Sn(s) + 2 CO₂(g) → SnO₂(s) + 2 CO(g)
This reaction is the reverse of the original reaction without any coefficient changes. Reversing the reaction changes the sign of ΔG°:
ΔG° = +194 kJ
3. Reaction: SnO₂(s) + 2 CO₂(g) → Sn(s) + 2 CO(g)
This reaction is not directly related to the original reaction. To determine its ΔG°, we need to consider the following steps:
- The original reaction: SnO₂(s) + 2 CO(g) → Sn(s) + 2 CO₂(g) with ΔG° = -194 kJ.
- Reversing this reaction: Sn(s) + 2 CO₂(g) → SnO₂(s) + 2 CO(g) with ΔG° = +194 kJ.
Therefore, the ΔG° for SnO₂(s) + 2 CO₂(g) → Sn(s) + 2 CO(g) is -194 kJ.
Summary:
| Reaction | ΔG° (kJ) | |—|—| | 2 Sn(s) + 4 CO₂(g) → 2 SnO₂(s) + 4 CO(g) | +388 | | Sn(s) + 2 CO₂(g) → SnO₂(s) + 2 CO(g) | +194 | | SnO₂(s) + 2 CO₂(g) → Sn(s) + 2 CO(g) | -194 |
Explanation:
The Gibbs free energy change (ΔG°) indicates the spontaneity of a reaction under standard conditions. A negative ΔG° signifies a spontaneous reaction, while a positive ΔG° indicates non-spontaneity. When a reaction is reversed, the sign of ΔG° changes because the direction of spontaneity is inverted. Additionally, scaling the stoichiometric coefficients of a reaction by a factor scales ΔG° by the same factor, as ΔG° is an extensive property proportional to the amount of reactants and products involved. These principles allow us to calculate the ΔG° values for related reactions based on known ΔG° values.