Write a balanced net ionic equation to desribe the reaction

Write a balanced net ionic equation to desribe the reaction that occurs when 50.0 mL of 0.100 M nitric acid and 50.0 mL of 0.100 M sodium cyanide solutions are mixed, determine the numerical value of the equilibrium constant for each of the reactions.

Solution

The molecular reaaction is

HNO3 (aq) + NaCN(aq) ---------------> HCN(aq) + NaNO3(aq)

50x0.1 50x0.1 0 0 initial mmoles

0 0 5 5 after reaction

Thus the net ionic equation is

H+ (aq) + CN-(aq) <-------------> HCN (aq)

The equilibrium constant for this equilibrium is

Keq = [HCN]/[H+][CN-]

which is reciprocal of the Ka , dissociation constant of HCN

Thus Keq for this reaction = 1/Ka of HCN

=1/6.17x10^-10

= 1.62x10⁹