`H_2S` is more acidic than `H_2O` because :

Options

A. Oxygen is more electronegative than sulphur
B. Atomic number of sulphur is higher than oxygen.
C. H-S bond dissociation energy is less as compared to H-O bond
D. H-O bond dissociation energy is less also compared to H-S bond

Answer

To determine why \( H_2S \) is more acidic than \( H_2O \), we can analyze the properties of both compounds and their ability to donate protons (H⁺ ions). Here’s a step-by-step solution:

### Step 1: Understand Acidity
Acidity is defined by a substance's ability to donate protons (H⁺ ions). The more readily a compound can lose a proton, the stronger its acidity.

**Hint:** Remember that the strength of an acid is related to how easily it can release H⁺ ions.

### Step 2: Compare the Compounds
We are comparing \( H_2S \) (hydrogen sulfide) and \( H_2O \) (water). Both can dissociate to release protons:
- \( H_2S \rightarrow H^+ + HS^- \)
- \( H_2O \rightarrow H^+ + OH^- \)

**Hint:** Look at the products of the dissociation and consider their stability.

### Step 3: Analyze the Stability of Conjugate Bases
The conjugate base of \( H_2S \) is \( HS^- \) and the conjugate base of \( H_2O \) is \( OH^- \). The stability of these conjugate bases plays a crucial role in determining acidity.

**Hint:** The more stable the conjugate base, the stronger the acid.

### Step 4: Consider Atomic Size and Charge Distribution
Sulfur (S) is larger than oxygen (O). This larger atomic size allows for better dispersion of the negative charge on \( HS^- \) compared to \( OH^- \). A more dispersed charge generally leads to greater stability.

**Hint:** Think about how atomic size affects the distribution of charge and stability.

### Step 5: Bond Strength Comparison
The bond dissociation energy of the \( H-S \) bond in \( H_2S \) is lower than that of the \( H-O \) bond in \( H_2O \). This means that it takes less energy to break the \( H-S \) bond, allowing \( H_2S \) to lose a proton more easily.

**Hint:** Recall that weaker bonds are easier to break, which contributes to higher acidity.

### Step 6: Conclusion
Since \( HS^- \) is more stable than \( OH^- \) and the \( H-S \) bond is weaker than the \( H-O \) bond, \( H_2S \) is more acidic than \( H_2O \).

**Final Statement:** Therefore, \( H_2S \) is more acidic than \( H_2O \) because it can more readily lose a proton due to the stability of its conjugate base and the weaker bond strength.

---