Consider the following chemical equation in equilibrium:

[tex]H_2SO_4 (aq) \Leftrightarrow 2 H^{+} + SO_4^{2-}[/tex]

What will happen to the chemical equilibrium if HCl is added to the system?

A. The chemical equilibrium will shift to the right.
B. The chemical equilibrium will be lost permanently.
C. The chemical equilibrium will not be affected.
D. The chemical equilibrium will shift to the left.



Answer :

To determine what will happen to the chemical equilibrium when HCl is added to the system, let's break down the effects step-by-step:

1. Understand the Chemical Equilibrium:
The given equilibrium equation is:
[tex]\[ H_2SO_4 (aq) \Leftrightarrow 2 H^+ (aq) + SO_4^{2-} (aq) \][/tex]
In this equilibrium, sulfuric acid (H₂SO₄) dissociates into hydrogen ions (H⁺) and sulfate ions (SO₄²⁻).

2. Effect of Adding HCl:
- HCl is a strong acid and dissociates completely in water into H⁺ ions and Cl⁻ ions:
[tex]\[ HCl (aq) \rightarrow H^+ (aq) + Cl^- (aq) \][/tex]
- Adding HCl to the solution increases the concentration of H⁺ ions.

3. Le Chatelier's Principle:
According to Le Chatelier's Principle, if a system at equilibrium is subjected to a change in concentration, temperature, volume, or pressure, the system will adjust itself to partially counteract the effect of the change and a new equilibrium will be established.
- In this case, by adding HCl, you are increasing the concentration of H⁺ ions in the solution.

4. Shift in Equilibrium:
- With the increase in H⁺ ion concentration, the equilibrium will shift to counteract this change.
- The system will shift to decrease the concentration of H⁺ ions.
- This means the equilibrium will shift towards the production of more H₂SO₄, moving the reaction to the left.

Therefore, the chemical equilibrium will shift to the left when HCl is added to the system. The correct answer is:
- The chemical equilibrium will shift to the left.