Question

When equal moles of each reactant are used, which type of reaction will produce a slightly basic solution?

strong acid – strong base

strong acid – weak base

weak acid – strong base

None of these are correct.

Answer 1

Weak acid – strong base. A solution of a salt of a weak acid and a strong base will be basic.

For example, NaF is the salt of the strong base NaOH and the weak acid HF.

The conjugate acid of a strong base [OH^(-)] is weak (H_2O), but the conjugate base of a weak acid is strong. It will react with the water to produce hydroxide ions [OH^(-)].

F^(-) + H_2O ⇌ HF + OH^(-)

“Strong acid – strong base” is wrong. The solution will be neutral.

“Strong acid – weak base” is wrong. The solution will be acidic.