Textbook Problem

Upon dissolving InCl(s) in HCl, In⁺(aq) undergoes a disproportionation reaction according to the following unbalanced equation:

${\text{In}}^{+}\left(aq\right)\to \text{In}\left(s\right)+{\text{In}}^{\text{3+}}\left(aq\right)$

This disproportionation follows first-order kinetics with a half-life of 667 s. What is the concentration of In⁺(aq) after 1.25 h if the initial solution of In⁺(aq) was prepared by dissolving 2.38 g InCl(s) in dilute HCl to make 5.00 × 10² mL of solution? What mass of In(s) is formed after 1.25 h?