Contrast the action of heat on the following with reason: a. Na_(2)CO_(3) and CaCO_(3) b. MgCl_(2).6H_(2)O and CaCl_(2).6H_(2)Oc. Ca(NO_(3))_(2) and NaO_(3)

Contrast the action of heat on the following with reason: a. Na_(2)CO_

1.	Contrast the action of heat on the following with reason: a. Na_(2)CO_(3) and CaCO_(3) b. MgCl_(2).6H_(2)O and CaCl_(2).6H_(2)Oc. Ca(NO_(3))_(2) and NaO_(3)
Answer» SOLUTION :(a). On heating, the DECAHYDRATE loses water of crystallisation to form monohydrate. Above `373 K`, they completely become anhydrous and become a powder. `Na_(2)CO_(3).10H_(2)Ooverset(373 K)(rarr)Na_(2)CO_(3).H_(2)O+9H_(2)O` `NaCO_(3).H_(2)O overset(above)underset(373 K)(rarr)underset((soda ash))(Na_(2)CO_(3))+H_(2)O` The `Na_(2)CO_(3)` or soda ash is thermally very stable and does not decompose UPON heating. When `CaCO_(3)` is heated above `1200 K`, it decompose to evolve carbon dioxide. `CaCO_(3)overset(1200 K)(rarr)CaO+CO_(2)` (b). When `MgCl_(2).6H_(2)O` is heated, it decomposes to give magnesium oxide `(MgO)`. `MgCl_(2).6H_(2)OrarrMgO+5H_(2)O+2HCl` The halide of calcium is hyproscopic. The `CaCl_(2)6 H_(2)O` get dehydrated upon heating. `CaCl_(2).6 H_(2)O overset(heat)(rarr)CaCl_(2)+6 H_(2)O` On this basis it is used as a dehydrating agent. (c ). When calcium nitrate is heated, it decompose and forms the oxide. `2Ca(NO_(3))_(2)overset(Heat)(rarr)2CaO+4NO_(2)+O_(2)` When sodium nitrate is heated strongly it gives nitrates and evolve oxygen. `2NaNO_(3)overset(Heat)(rarr)2NaNO_(2)+O_(2)uarr.`