example of thermally stable hydroxide
Answers
Explanation:
mg(oH)2 magnesium hydroxide is an example of thermally stable hydroxide
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Answer:
(i) Solubility
(ii) Thermal stability
Explanation:
(i) Solubility
Nitrates, carbonates and sulphates of alkali metals are water soluble. On moving down the group, the solubility increases. This is because their lattice energies decreases more rapidly than their hydration energies.
Alkaline earth metal nitrates are water soluble. On moving down the group, their solubility decreases. This is because their hydration energies decreases more rapidly than their lattice energies.
Alkaline earth metal carbonates and sulphates have lower solubility than alkali metal carbonates and sulphates. The solubility of alkaline metal carbonates and sulphates decreases with decrease in hydration energy as we move down the group.
(ii) Thermal stability
Alkali and alkaline earth metal nitrates decompose on heating. On heating alkali metal (Na, K, Rb and Cs) decompose to form metal nitrites and oxygen.
2MNO
3
heat
2MnO
2
+O
2
Alkaline earth metal nitrates decompose on heating to give metal oxide, nitrogen dioxide and oxygen.
2M(NO
3
)
2
heat
2MO+4NO
2
+O
2
(M=Be,Mg,Ca,Sr,Ba)
Lithium nitrate (like magnesium nitrate) decomposes to form metal oxide, nitrgen dioxide and oxygen.
4LiNO
3
Heat
2Li
2
O+4NO
2
+O
2
This is because small sized Li+ ion cannot stabilize nitrate ion.
Alkaline earth metal carbonates have less stability towards heat and decompose to carbon dioxide.
MCO
3
→MO+CO
2
On moving down the group, the stability of alkaline earth metal carbonates increases. Because of diagonal relationship, lithium carbonate decomposes similar to magnesium carbonate.
Li
2
CO
3
heat
Li
2
O+CO
2
Other alkali metal carbonates being stable to heat do not decompose.
On heating, alkaline earth metal sulphates decompose to form SO
3
MSO
4
heat
MO+SO
3
On moving down the group, the electropositive characteer and the thermal stability of alkaline earth metal sulphates increases.
Except Li
2
SO
4
, the alkali metal sulphates are stable and do not decompose easily.
Li
2
SO
4
decomposes like MgSO
4
to give SO
3
Li
2
SO
4
heat
Li
2
O+SO
3
MgSO
4
heat
MgO+SO
3