Name the three factors which determine the stability of a particular oxidation state in solution.

Answer

To determine the stability of a particular oxidation state in a solution, we need to consider three key factors. Here’s a step-by-step breakdown of these factors:

### Step 1: Enthalpy of Sublimation
- **Explanation**: The first factor is the enthalpy of sublimation. This is the energy required to convert a solid metal atom into a gaseous metal atom. This process requires energy input, hence it is considered positive.
- **Hint**: Remember that sublimation involves changing a solid directly into a gas, which requires energy.

### Step 2: Ionization Energy
- **Explanation**: The second factor is the ionization energy. This is the energy needed to remove the outermost electron from a gaseous metal atom, converting it into a gaseous metal ion. This also requires energy input, so it is considered positive.
- **Hint**: Ionization energy is related to how tightly an atom holds onto its electrons; higher ionization energy means more energy is needed to remove an electron.

### Step 3: Enthalpy of Hydration
- **Explanation**: The third factor is the enthalpy of hydration. This is the energy released when a gaseous metal ion is surrounded by water molecules and becomes hydrated. This process releases energy, so it is considered negative.
- **Hint**: Hydration energy is crucial because it indicates how much energy is released when ions interact with water, which stabilizes the ions in solution.

### Conclusion
- The overall stability of the oxidation state is determined by the total energy change, which is the sum of the enthalpy of sublimation and ionization energy (both positive) minus the enthalpy of hydration (negative). If the total energy change is negative, the oxidation state is stable; if it is positive, the oxidation state is unstable.

### Summary of Factors
1. **Enthalpy of Sublimation** (positive)
2. **Ionization Energy** (positive)
3. **Enthalpy of Hydration** (negative)

### Overall Stability
- **Stable Oxidation State**: Total energy change is negative.
- **Unstable Oxidation State**: Total energy change is positive.