Question

On heating, calcium carbonate gets converted into calcium oxide and carbon dioxide.
(a) Is this a physicl or a chemical change ?
(b) Can you prepare one acidic and one basic solution by using the products formed in the above process ?
If so, write the chemical equation involved.

Answer 1

(a) It is chemical change. The chemical equation for the reaction is :
calcium carbonate `overset("heat")rarr` Calcium oxide + Carbon dioxide
(b) By adding water to calcium oxide taken in a test tube, a basic solution results. It contains calcium hydroxide
Calcium oxide + Water `rarr` Calcium hydroxide
By passing carbon dioxide through water taken in a tube, carbonic acid is formed. The solution is of acidic nature
Carbon dioxide + Water `rarr` Carbonic acid
Notes : All the three chemical equations are word equations. Symbol equations can also be written for these. For example,
`CaCO_(3) overset("heat")rarr CaO + CO_(2)`
`CaO + H_(2)O rarrCa(OH)_(2)` (basic solution)
`CO_(2) + H_(2)O rarr H_(2)CO_(3)` (acidic solution)
However, you will learn about these in the next class.