class 10 question – Q. 1. A solution of substance ‘X’ is used for white “Washing”.
(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above, with water.
(i) A solution of substance which is used for white Washing is ”quick lime (calcium oxide) ” and the chemical formula of quick lime (calcium oxide) is CaO.
(ii) When quick lime (calcium oxide) (CaO) is mixed with water, the following reaction takes place as follows –
Quick lime + Water → Slaked lime (Calcium Hydroxide)
CaO(s) + H2
O(l) → Ca(OH)2
: The white substance (slaked lime) which has chemical formula Ca(OH)2
is applied on walls. slaked lime further reacts with carbon dioxide (CO2
) present in air forms a thin shiny layer of calcium carbonate (CaCO3
this chemical reaction take place as follows –
Calcium Hydroxide + carbon dioxide → Calcium carbonate + water