Calculate the pH of a 0.430 M solution of NH4I; i have no idea how to attempt this.?

Question

Calculate the pH of a 0.430 M solution of NH4I

Answer 1

When NH4I dissolves, the NH4+ ions act as a weak acid, transferring some of their protons to water:

NH4+ + H2O --> NH3 + H3O+

In your text book, you should be able to find the value for Ka for ammonium ions. If it isn't listed in the table, you might be able to find Kb for ammonia. If you divide 1 X 10^-14 by Kb, you calculate Ka.

Now, write the equation for Ka, let [H3O+] =[NH3] = x. The [NH4+] will equal 0.43 M.

Solve for x, take the -log of that and you're there.