Question

In a solution of acetic acid (vinegar) in water, the pH is 5.0. Which expression identifies the concentration of hydrogen ions in the solution?

Answer 1

We can calculate for the hydrogen ion concentration by taking the antilog of the negative pH or simply by taking 10 to the power of the negative pH. For the acetic acid solution of pH equal to 5.0, the equation of the reaction is 
     CH3COOH(aq) + H2O(l) ↔ CH3COO(aq) + H3O+(aq)
and the concentration of hydrogen ions would therefore be
     [H+ ] = 10^-pH = 10^-5.0 = 1 x 10^-5 M.