Proton transfer reactions Questions

Making an acidic buffer

Mix a weak acid with a soluble salt of the acid

OR

Add strong base to excess of weak acid

What is a Brønsted–Lowry acid?

A species that donates a proton (H⁺).

What is a Brønsted–Lowry base?

A species that accepts a proton (H⁺).

How can you identify a conjugate acid–base pair?

They differ by one proton (H⁺); the acid has one more H⁺ than its conjugate base.

What are the products when KHCO₃ reacts with H₂SO₄?

K₂SO₄, H₂O, and CO₂.

What does the pH value indicate about acid strength?

Lower pH = stronger acid; higher pH = weaker acid (for same concentration).

What is the ionic product of water (Kw) at 25°C?

Kw = 1.0 × 10⁻¹⁴ mol² dm⁻⁶

How do you calculate [H⁺] from [OH⁻]?

[H⁺] = Kw / [OH⁻]

How do you calculate pH?

pH = –log[H⁺]

Why are weak acids poor conductors of electricity?

They only partially ionise, producing fewer ions in solution.

Do weak acids react with carbonates?

Yes — they still produce CO₂, though less vigorously.

What is the pH trend for the solutions: HCl, CH₃COOH, NH₃, NaOH?

HCl < CH₃COOH < NH₃ < NaOH

How do you identify the Brønsted–Lowry acid in a reaction?

Look for the species that donates a proton (loses H⁺).

What is formed when a weak acid reacts with a strong base?

A salt and water; the salt may hydrolyse to form a basic solution.

What makes a good buffer solution?

A weak acid/base and its conjugate salt in similar concentrations.

What is the Ka expression for a weak acid?

Ka = [H⁺][A⁻] / [HA]

What is the relationship between Ka, Kb and Kw?

Ka × Kb = Kw

What is the effect of dilution on pH of a strong acid?

It increases the pH but the acid remains strong (still fully dissociated).

What is the pH at the equivalence point for a strong acid + strong base titration?

Approximately pH 7.

What is the pH at the equivalence point for a weak acid + strong base titration?

Greater than pH 7 due to the basic salt formed.

How can you recognise salt hydrolysis?

The salt from a weak acid/base affects the pH of the solution.