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

The solubility and thermal stability of nitrates, carbonates, and sulfates vary significantly between alkali metals and alkaline earth metals. Here’s a comparison:

Nitrates
Solubility:

Alkali Metals: Alkali metal nitrates (LiNO₃, NaNO₃, KNO₃, etc.) are highly soluble in water. The solubility generally increases down the group.
Alkaline Earth Metals: Alkaline earth metal nitrates (Mg(NO₃)₂, Ca(NO₃)₂, Sr(NO₃)₂, Ba(NO₃)₂) are also soluble in water, though not as soluble as alkali metal nitrates. Solubility increases down the group.
Thermal Stability:

Alkali Metals: Alkali metal nitrates decompose upon heating to give nitrites and oxygen. For example:
2
 
KNO
3
→
2
 
KNO
2
+
O
2
2KNO
3
​
→2KNO
2
​
+O
2
​

Alkaline Earth Metals: Alkaline earth metal nitrates decompose to give the oxide, nitrogen dioxide, and oxygen. For example:
2
 
Ca(NO
3
)
2
→
2
 
CaO
+
4
 
NO
2
+
O
2
2Ca(NO
3
​
)
2
​
→2CaO+4NO
2
​
+O
2
​


Alkaline earth metal nitrates are less stable than alkali metal nitrates and decompose at lower temperatures.
Carbonates
Solubility:

Alkali Metals: Alkali metal carbonates (Li₂CO₃, Na₂CO₃, K₂CO₃, etc.) are soluble in water, with solubility generally increasing down the group.
Alkaline Earth Metals: Alkaline earth metal carbonates (MgCO₃, CaCO₃, SrCO₃, BaCO₃) are sparingly soluble in water. Their solubility decreases down the group.
Thermal Stability:

Alkali Metals: Alkali metal carbonates are generally thermally stable and do not decompose easily upon heating.
Alkaline Earth Metals: Alkaline earth metal carbonates decompose upon heating to form the oxide and carbon dioxide. For example:
CaCO
3
→
CaO
+
CO
2
CaCO
3
​
→CaO+CO
2
​


The thermal stability increases down the group, with BaCO₃ being more thermally stable than MgCO₃.
Sulfates
Solubility:

Alkali Metals: Alkali metal sulfates (Li₂SO₄, Na₂SO₄, K₂SO₄, etc.) are soluble in water, with solubility generally increasing down the group.
Alkaline Earth Metals: Alkaline earth metal sulfates (MgSO₄, CaSO₄, SrSO₄, BaSO₄) vary in solubility. MgSO₄ is quite soluble in water, while CaSO₄ is sparingly soluble. SrSO₄ and BaSO₄ are practically insoluble in water. Solubility decreases down the group.
Thermal Stability:

Alkali Metals: Alkali metal sulfates are thermally stable and do not decompose upon heating.
Alkaline Earth Metals: Alkaline earth metal sulfates are also thermally stable, though heating can cause some decomposition in extreme conditions, typically forming the oxide and sulfur trioxide.
In summary:

Alkali metal compounds are generally more soluble in water compared to their alkaline earth metal counterparts.
Alkali metal compounds (especially nitrates) tend to have higher thermal stability than alkaline earth metal compounds.
Alkaline earth metal carbonates and sulfates are less soluble and decompose more readily upon heating compared to alkali metal carbonates and sulfates.