When you add sodium hydrogen carbonate to acetic acid in a test tube, a gas liberates
immediately with a brick effervescence. Name this gas. Describe the method of testing
this gas.

Explanation

When sodium hydrogen carbonate is added to acetic acid in a test tube, then a brisk effer-
vescence is observed due to the liberation of `CO_(2)` gas which is colourless and odourless.
`CH_(3) COOH(aq) + NaHCO_(3)(aq)to CH_(3) COONa+H_(2) O + CO_(2)uarr`
when `CO_(2) ` is passed through lime water, lime water turns milky due to the formation of
`CaCO_(3)` (calcium carbonate) .
`underset("Lime water")(Ca(OH)_(2)(aq)) + CO_(2) (g) to underset(White ppt.)(CaCO_(3) darr) + H_(2) O `
Milkines of the lime water disappears when `CO_(2)` gas in passed for considerable time due
to the formation a `Ca (HCO_(3))_(2)`.
`CaCO_(3) + H_(2) O + CO_(2) to underset(("Soluble in water"))(Ca(HCO_(3))_(2)(aq))` .