10.15. Compare the solubility and thermal stability of the following compounds of the alkali metals with those of the alkaline earth metals.
(a) Nitrates (b) Carbonates (c) Sulphates.

<p><strong> (a)&nbsp;</strong>Nitrates of both group 1 and group 2 elements are soluble in water because hydration energy is more than the lattice energy.<br>Nitrates of both group 1 and group 2 elements are thermally unstable but they decompose differently except LiCO₃&nbsp;e.g.</p><p>2NaNO₃ →2NaNO₂ + O₂</p><p>2KNO₃ →2KNO₂ + O₂</p><p>4LiNO₃ →2MgO + 4 NO₂ + O₂</p><p>2Mg (NO₃)₂ →2MgO + 4NO₂ + O₂<br><br><strong> (b) </strong>Carbonates of group 1 elements are soluble in water except Li₂CO₃&nbsp;They are also thermally stable except Li₂CO₃.</p><p>Li₂CO₃ →Li₂O + CO₂<br>Group 2 carbonates are insoluble in water because their lattice energy is higher than hydration energy.<br>Thermal stability of carbonates of group 2 increases down the group because lattice energy goes on increasing due to increase in ionic character.</p><p><strong> (c) </strong>Sulphates of group 1 are soluble in water except Li₂SO₄. They are thermally stable.<br>Solubility of sulphates of group 2 decreases down the group because Lattice energy dominates over hydration energy.<br>Sulphates of group 2 elements are thermally stable and increasing down the group due to increases in Lattice energy.</p>

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