Precipitate of group IV cations takes place when `H_(2)S` is

Options

A. Highly ionised
B. Less ionised
C. Not ionised
D. None of these

Answer

To solve the question regarding the precipitation of group IV cations when H₂S is involved, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding Group IV Cations**:
Group IV cations typically include metals like lead (Pb²⁺), bismuth (Bi³⁺), and copper (Cu²⁺). These cations can form insoluble sulfides when reacted with hydrogen sulfide (H₂S).

**Hint**: Identify the common cations in group IV that form precipitates with H₂S.

2. **Role of H₂S**:
Hydrogen sulfide (H₂S) acts as a source of sulfide ions (S²⁻) in solution. The precipitation of group IV cations occurs when the concentration of sulfide ions exceeds the solubility product of the respective sulfides.

**Hint**: Recall that H₂S dissociates in solution to provide sulfide ions.

3. **Ionization of H₂S**:
The extent to which H₂S ionizes in solution is crucial. When H₂S is highly ionized, it means that there is a greater concentration of sulfide ions available to react with the cations.

**Hint**: Consider how the ionization of H₂S affects the availability of sulfide ions.

4. **Precipitation Condition**:
For precipitation to occur, the ionic product (the product of the concentrations of the ions in solution) must exceed the solubility product (Ksp) of the sulfide formed. This is more likely to happen when H₂S is highly ionized, leading to a higher concentration of S²⁻ ions.

**Hint**: Remember the relationship between ionic product and solubility product.

5. **Presence of NH₄OH**:
The presence of ammonium hydroxide (NH₄OH) can increase the concentration of hydroxide ions (OH⁻) in the solution. This can shift the equilibrium of H₂S, promoting its ionization and thus increasing the concentration of sulfide ions.

**Hint**: Think about how adding NH₄OH influences the ionization of H₂S.

6. **Conclusion**:
Therefore, the precipitation of group IV cations as sulfides occurs when H₂S is highly ionized, which increases the concentration of sulfide ions in the solution, leading to the formation of insoluble sulfides.

**Final Answer**: Precipitate of group IV cations takes place when H₂S is highly ionized.