Explain why this combination of compounds can or cannot make a buffer solution. Hint: apply definition of a buffer, mechanism of its action and consider whether the compound is acid (weak/strong) or base (weak/strong). HF (0.2 mol) and NaOH (0.1 mol)

This combination can make a buffer

Explanation:

A buffer is defined as an aqueous mixture of a weak acid and its conjugate base, or vice versa.

In the problem, HF is a weak acid, and its conjugate base is F⁻.

When NaOH reacts with HF, F⁻, Na⁺ and H₂O are produced as follows:

NaOH + HF → F⁻ + Na⁺ + H₂O

As there are initially 0.2mol of HF and 0.1mol NaOH, after the reaction you will have:

0.1mol HF and 0.1mol F⁻. As both, the weak acic and the conjugate base are present: