Question

What change will be caused by addition of a small amount of hcl to a solution containing fluoride ions and hydrogen fluoride?

Answer 1

Answer:

• The addition of a small amount of HCl to a solution containing fluoride ions and hydrogen fluoride will cause the equilibrium shift to the production of more hydrogen fluoride.

Explanation:

The solution containing fluoride ions and hydrogen fluoride (a weak acid) may be chemically represented by this equilibrium equation:

• F⁻ (aq) + H⁺ (aq) ⇄ HF (aq)

The HCl, a strong acid, added will ionize in water according to this chemical equation:

• HCl (aq)  → H⁺ (aq) + Cl⁻ (aq)

Then, following Le Chatelir's principle, the addtion of H⁺ ions coming from the HCl dissociation, will increase the concentration of H⁺ in the solution, driving to the consumption of some F⁻ ions, and the production of more HF acid. This is a shift of the equilbrium toward the HF side.