Consider the following three statements regarding Hydrogen chemistry: I. The hydration enthalpy of t — Hydrogen Chemistry Question
Question
Consider the following three statements regarding Hydrogen chemistry: I. The hydration enthalpy of the $H^+$ ion is extremely high due to its infinitesimal size. II. The decomposition of $H_2O_2$ is an example of a disproportionation reaction. III. Permutit ($Na_2Al_2Si_2O_8$) softens water by precipitating $Ca^{2+}$ ions as insoluble calcium silicates. Which of the statements is/are correct?
💡 Solution & Explanation
Statement I is correct: $H^+$ has a size of $\sim 1.5 \times 10^{-3}$ pm, yielding massive charge density and hydration energy (forming $H_3O^+$). Statement II is correct: $H_2O_2$ (O is -1) decomposes to $H_2O$ (O is -2) and $O_2$ (O is 0). Statement III is incorrect: Permutit works by *ion-exchange*, trapping the $Ca^{2+}$ inside the solid resin matrix and releasing $Na^+$ into the water, NOT by forming physical precipitates in the bulk liquid.