Carbon dioxide gas is detected by its action on

Options

A. lime water
B. baryta water
C. both (1) and (2)
D. blue litmus

Answer

C

Explanation

To identify `CO_(2)`, the lime water `[Ca(OH)_(2)]` test or baryta water `[Ba(OH)_(2)]` test is used. In this test, a gas is bubbled into a saturated solution of calcium hydroxide (lime water) or barium hydroxide (baryta water). When the gas is `CO_(2)`, the lime water or baryta water turns milky as a white precipitate of `CaCO_(3)` or `BaCO_(3)` is formed:
`CO_(2)(g) + Ca(OH)_(2)(aq.) rarr CaCO_(3)(s) + H_(2)O(l)`
`CO_(2)(g) + Ba(OH)_(2)(aq.) rarr BaCO_(3)(s) + H_(2)O(l)`
The additon of more `CO_(2)` results in the disappearance of precipitate as soluble calcium hydrogen carbonate or barium hydrogen carbonate forms:
`CO_(2)(g) + CaCO_(3)(s) + H_(2)O(l) rarr Ca^(2+)(aq.) + 2HCO_(3)^(-)(aq.)`