Uranium in water decays to form Zn21 and Sm by fission. Uranium has a half-life of 7 × 1...

Uranium in water decays to form Zn21 and Sm by fission. Uranium has a half-life of 7 × 10⁸ years. The zinc ions react with water and act as a weak acid according to the following equation:

Assuming that this is the only radioactive decay of any significance and that neither Sm nor U acts as a weak acid, how many years will it take a 1.00 M solution of U to achieve a pH of 6.0?