Subject: Inorganic Chemistry · Chapter: Main Group Elements · Topic: Main Group Elements – General · Exam: CSIR-NET 2019 · Marks: 2 · Difficulty: Hard
Choose the correct statement(s) among the following (I) $\mathrm{LiF}$ is more soluble than $\mathrm{LiClO}_{\mathrm{4}}$ in water. (III) The heat of hydration of $\mathrm{Li}^{+}(\mathrm{g})$ is greater than that of $\mathrm{Na}^{+}(\mathrm{g})$
(a)I and II
(b)I and III
(c)II and III
(d)III Only
Answer
Answer (as printed): C
Explanation
• $\mathrm{LiF}$ is sparingly soluble in water, but for large anions such as $\mathrm{ClO_4^{-}}$, the $\mathrm{Li^{+}}$ salts are soluble in water.• Standard reduction potential $[E^{0}]$ of Li is more negative than that of Na.$\mathrm{Li^{+}(aq)} + e^{-} \rightarrow \mathrm{Li(s)}$, $[E^{0}]_{\text{red}} = -3.04$$\mathrm{Na^{+}(aq)} + e^{-} \rightarrow \mathrm{Na(s)}$, $[E^{0}]_{\text{red}} = -2.71$• Enthalpy of hydration: $\mathrm{Li^{+}(g)}$ [$-520\,\mathrm{kJ/mol}$] > $\mathrm{Na^{+}(g)}$ [$-406\,\mathrm{kJ/mol}$]