Which of the following alkali metal bicarbonates readily decomposes?

Options

A. `LiHCO_(3)`
B. `KHCO_(3)`
C. `CsHCO_(3)`
D. `NaHCO_(3)`

Answer

To determine which alkali metal bicarbonate readily decomposes, we need to analyze the thermal stability of the bicarbonates of the alkali metals: lithium, sodium, potassium, and cesium.

### Step-by-Step Solution:

1. **Identify the Alkali Metal Bicarbonates:**
The alkali metal bicarbonates in question are:
- Lithium bicarbonate (LiHCO₃)
- Sodium bicarbonate (NaHCO₃)
- Potassium bicarbonate (KHCO₃)
- Cesium bicarbonate (CsHCO₃)

2. **Understand Thermal Stability:**
The thermal stability of bicarbonates is influenced by the polarizing power of the cation. The polarizing power is inversely related to the size of the cation; smaller cations have higher polarizing power.

3. **Analyze the Cations:**
- **Lithium (Li⁺)**: Smallest cation, highest polarizing power.
- **Sodium (Na⁺)**: Larger than Li⁺, lower polarizing power.
- **Potassium (K⁺)**: Larger than Na⁺, even lower polarizing power.
- **Cesium (Cs⁺)**: Largest cation, lowest polarizing power.

4. **Determine Stability:**
- Since lithium has the highest polarizing power, lithium bicarbonate (LiHCO₃) is the least stable among the bicarbonates. This means it will decompose more readily upon heating.
- The other bicarbonates (NaHCO₃, KHCO₃, CsHCO₃) are more stable due to their larger cations, which have lower polarizing power.

5. **Decomposition Reaction:**
When lithium bicarbonate is heated, it decomposes as follows:
\[ 2 \text{LiHCO}_3 \rightarrow \text{Li}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O} \]
This shows that lithium bicarbonate readily decomposes into lithium carbonate, carbon dioxide, and water.

6. **Conclusion:**
Based on the analysis, the alkali metal bicarbonate that readily decomposes is **lithium bicarbonate (LiHCO₃)**.

### Final Answer:
**Lithium bicarbonate (LiHCO₃) readily decomposes.**