Equimolar solution of the following substances were prepared separately. Which one of these will record the highest pH value?

Options

A. `BaCl_2`
B. ` AlCl_3`
C. ` LiCl`
D. ` BeCl_2`

Answer

To determine which equimolar solution of the given substances will record the highest pH value, we need to analyze the basicity of each substance. The pH scale ranges from 0 to 14, with 7 being neutral. A higher pH indicates a more basic solution.

### Step-by-Step Solution:

1. **Identify the Substances**: We have four substances to consider: Barium Chloride (BaCl₂), Aluminium Chloride (AlCl₃), Lithium Chloride (LiCl), and Beryllium Chloride (BeCl₂).

2. **Understand the Formation**: Each of these chlorides is formed from a strong acid (HCl) and their respective hydroxides:
- Barium Chloride from Barium Hydroxide (Ba(OH)₂)
- Aluminium Chloride from Aluminium Hydroxide (Al(OH)₃)
- Lithium Chloride from Lithium Hydroxide (LiOH)
- Beryllium Chloride from Beryllium Hydroxide (Be(OH)₂)

3. **Consider the Strength of Bases**: The basicity of the solutions will depend on the strength of their corresponding hydroxides:
- **Barium Hydroxide (Ba(OH)₂)** is a strong base and dissociates completely in solution, producing two hydroxide ions (OH⁻).
- **Aluminium Hydroxide (Al(OH)₃)** is a weak base and does not dissociate completely, producing fewer hydroxide ions.
- **Lithium Hydroxide (LiOH)** is a strong base but produces only one hydroxide ion.
- **Beryllium Hydroxide (Be(OH)₂)** is also a weak base and does not dissociate completely.

4. **Compare the Hydroxide Ion Production**:
- Barium Hydroxide produces 2 OH⁻ ions per formula unit, leading to a higher concentration of hydroxide ions in solution.
- Lithium Hydroxide produces 1 OH⁻ ion per formula unit.
- Aluminium and Beryllium Hydroxides produce even fewer hydroxide ions due to their weak basic nature.

5. **Determine the pH**: Since pH is a measure of the concentration of hydroxide ions in solution, the solution with the highest concentration of OH⁻ ions will have the highest pH. Therefore, Barium Chloride, which corresponds to Barium Hydroxide, will result in the highest pH value.

6. **Conclusion**: The substance that will record the highest pH value when prepared as an equimolar solution is **Barium Chloride (BaCl₂)**.

### Final Answer:
**Barium Chloride (BaCl₂)** will record the highest pH value.

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