Question

A hypothetical acid HA has a dissociation constant 1.8 𝑥 10ିଷ.

a. Write a balanced dissociation reaction of the acid

b. Write the equilibrium constant expression for the acid

c. If the initial concentration of the acid is 0.5 M, determine its hydrogen ion

concentration.

d. Calculate the ionization constant

e. Comment on the strength of the acid.

Answer 1

Start by writing a balanced chemical equation for the partial ionization of the acid

HA (aq] + H 2 O (l] ⇌ A − (aq] + H 3 O + (aq]HA(aq]+H2O(l]⇌A−(aq]+H3O+(aq]

Notice that you have 1:1

mole ratios across the board. For every mole of acid that ionizes in aqueous solution, you get one mole of its conjugate base and one mole of hydronium ions, H3O+