Final answer:
Without the acid dissociation constant (Ka) for hydrocyanic acid or the pH of the solution, we cannot calculate the hydroxide ion concentration. The concentration of hydroxide ions is typically found by first determining the hydronium ion concentration and then using the water dissociation equilibrium constant (Kw).
Step-by-step explanation:
To determine the hydroxide ion concentration from the hydrocyanic acid concentration, we need to consider that hydrocyanic acid (HCN) is a weak acid and does not fully dissociate in water. However, the question does not provide the acid dissociation constant (Ka) of hydrocyanic acid which is needed to calculate the extent of its dissociation and consequently the concentrations of the hydronium (H3O+) and hydroxide (OH-) ions in the solution. If we do have the Ka, we can set up an equation that would look like this:
Ka = [H3O+][CN-] / [HCN]
Without the Ka value or the pH of the solution, we cannot provide the exact hydroxide ion concentration. Typically, for such a solution, you would calculate the hydronium concentration first and then use the water dissociation equilibrium to find the hydroxide concentration:
1.0 x 10-14 = [H3O+][OH-]
If we assume that the acid fully dissociates (which is not true for a weak acid like HCN) and the concentration of HCN is equal to the hydronium ion concentration, then using the water dissociation constant (Kw = 1.0 x 10-14 at 25 °C), we can calculate the hydroxide ion concentration:
[OH-] = Kw / [H3O+]