Question

Hydrogen ion concentration of an aqueous solution is 1 × 10^-4 M.  The solution is diluted with equal volume of water.  Hydroxyl ion concentration of the resultant solution in terms of p×10^-10 mol dm^-3 . What is the value of p?

Answer 1

Correct Answer: 2

Explanation:
Given:Concentration of H⁺ ions,  [H⁺] = 1 × 10^-4 MThe solution is diluted with an equal volume of water.Hydroxyl ion solution in the resulting solution = p × 10^-10 mol dm^-3We have to find the value of p.Since, the solution is diluted with an equal volume of water, the concentration of H+ will become one-half of that of the original value. Concentration of [H+] ions = $\frac{1\times {10}^{-4}}{2}$= 0.5 × 10^-4 MWhen temperature is 25°C, the ionic product of water , Kw is given as:Kw =    [H⁺] [OH^-] = 1 × 10^-14  ....... (i)Substituting the value of [H⁺] in equation (i), we get[0.5 × 10^-4] [OH^-] = 1 × 10^-14[OH^-]= $\frac{1\times {10}^{-14}}{0.5\times {10}^{-4}}$= $\frac{1\times {10}^{-10}}{0.5}$= 2 × 10^-10  M or 2 × 10^-10 mol dm^-3Therefore, the value of p = 2.Hence, the correct answer is 2.00.