Equimolar solutions of the following compounds are prepared separately in water. Which will have the lowest pH value ?

Question

Consider the following equilibrium,

CO(g) + 2H₂(g) ↔ CH₃OH(g)

0.1 mol of CO along with a catalyst is present in a 2 dm³ flask maintained at 500 K. Hydrogen is introduced into the flask until the pressure is 5 bar and 0.04 mol of CH₃OH is formed. The K_p is ____ × 10^-3 (nearest integer).

Given: R = 0.08 dm³ bar K^-1mol^-1

Assume only methanol is formed as the product and the system follows ideal gas behaviour.

Answer 1

To determine which equimolar solution will have the lowest pH value, we need to consider the nature of the compounds in question and their effects on the pH of an aqueous solution.

Understanding the Compounds: We are given the following compounds: BeCl_2, SrCl_2, CaCl_2, and MgCl_2.
Nature of Each Compound: All given compounds are chlorides of alkaline earth metals (Group 2 elements). In water:
- BeCl_2 dissolves to form beryllium ions and chloride ions. Beryllium ions can hydrolyze, producing H^+ ions, making the solution acidic.
- MgCl_2, CaCl_2, and SrCl_2: These compounds also dissolve to produce ions, but the ability of these metal ions to hydrolyze and affect pH is much lower compared to beryllium.
Hydrolysis and pH:
- The hydrolysis of Be^{2+} ions is significant because of the small size and high charge density of the beryllium ion. It reacts with water to produce H^+ ions:
- Be^{2+} + 2H_2O \rightarrow [Be(OH)_2] + 2H^+
- This release of H^+ ions decreases the pH significantly, making the solution more acidic.
Comparison: Among the given compounds, BeCl_2 will produce a solution with the lowest pH due to its strong hydrolysis leading to a higher concentration of H^+ ions.

Therefore, the compound with the lowest pH value among the given options is BeCl_2.

Conclusion: The correct answer is BeCl_2 because of its strong ability to undergo hydrolysis and release H^+ ions, significantly lowering the pH compared to the other options.

Answer 2

To determine which equimolar solution will have the lowest pH value, we need to consider the nature of the compounds in question and their effects on the pH of an aqueous solution.

Understanding the Compounds: We are given the following compounds: BeCl_2, SrCl_2, CaCl_2, and MgCl_2.
Nature of Each Compound: All given compounds are chlorides of alkaline earth metals (Group 2 elements). In water:
- BeCl_2 dissolves to form beryllium ions and chloride ions. Beryllium ions can hydrolyze, producing H^+ ions, making the solution acidic.
- MgCl_2, CaCl_2, and SrCl_2: These compounds also dissolve to produce ions, but the ability of these metal ions to hydrolyze and affect pH is much lower compared to beryllium.
Hydrolysis and pH:
- The hydrolysis of Be^{2+} ions is significant because of the small size and high charge density of the beryllium ion. It reacts with water to produce H^+ ions:
- Be^{2+} + 2H_2O \rightarrow [Be(OH)_2] + 2H^+
- This release of H^+ ions decreases the pH significantly, making the solution more acidic.
Comparison: Among the given compounds, BeCl_2 will produce a solution with the lowest pH due to its strong hydrolysis leading to a higher concentration of H^+ ions.

Therefore, the compound with the lowest pH value among the given options is BeCl_2.

Conclusion: The correct answer is BeCl_2 because of its strong ability to undergo hydrolysis and release H^+ ions, significantly lowering the pH compared to the other options.

Equimolar solutions of the following compounds are prepared separately in water. Which will have the lowest pH value ?

The Correct Option is A

Solution and Explanation

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