Consider the `DeltaG_(f)^(@)` and `DeltaH_(f)^(@)` (kJ`//`mol) for the following oxides. Which can be most easily decomposed to form the metal and oxygen gas?

Options

A. `ZnO(DeltaG^(@)=-318.4, DeltaH^(@)=-348.3)`
B. `Cu_(2)O(DeltaG^(@)=-146.0, DeltaH^(@)=-168.8)`
C. `HgO(DeltaG^(@)=-58.5, DeltaH^(@)=-90.8)`
D. `PbO(DeltaG^(@)=-187.9, DeltaH^(@)=-217.3)`

Explanation

To determine which metal oxide can be most easily decomposed to form the metal and oxygen gas, we need to analyze the given standard Gibbs free energy of formation (ΔG_f^0) and standard enthalpy of formation (ΔH_f^0) values for the oxides. The key points to consider are:

1. **Understanding ΔG_f^0 and ΔH_f^0**:
- ΔG_f^0 indicates the stability of a compound. A more negative ΔG_f^0 suggests that the compound is more stable and less likely to decompose.
- ΔH_f^0 provides information about the heat change during the formation of the compound.

2. **Decomposition Reaction**:
- The decomposition of a metal oxide can be represented as:
\[ \text{Metal Oxide (MO)} \rightarrow \text{Metal (M)} + \frac{1}{2} \text{O}_2 \]
- For this reaction to occur spontaneously, the ΔG of the reaction must be negative.

3. **Evaluating the Oxides**:
- We will compare the ΔG_f^0 values of the given oxides. The oxide with the least negative ΔG_f^0 value will be the most likely to decompose because it indicates a higher tendency to break down into its constituent elements.

4. **Conclusion**:
- After analyzing the provided ΔG_f^0 values, we find that the oxide with the least negative value is HgO (ΔG_f^0 = -58.5 kJ/mol). This indicates that HgO is the least stable among the given oxides and will decompose most easily into mercury (Hg) and oxygen gas (O2).

Thus, the metal oxide that can be most easily decomposed to form the metal and oxygen gas is **HgO**.