Carbon dioxide is passed through lime water to form carbon dioxide and water along with evolution of heat
Answers
When carbon dioxide is passed through lime
water which is a diluted solution of Ca(OH) 2, it
turns milky due to the formation of calcium
carbonate which is CaCO3.
The reaction is like this:
Ca(OH) 2 + CO2 — CaCO3 + H20
If you pay a little more attention, you will be able
to observe that it is a neutralization reaction,
where base is Ca(OH)2 and acid is H2CO3 and a
salt CaCO3 and H20 are formed.
So, actually the above reaction is a short form of
actual reaction.
Actually CO2 is no more CO2 after dissolving in
water, it becomes H2CO3 via addition reaction as
shown :
CO2+H20 - H2CO3
Now, this CaCO3 is insoluble in water which is
the reason behind the milkiness of solution.
However if excess carbon dioxide is passed, the
milkiness disappears, think about it... milkiness
was due to CaCO3 and now the milkiness is
disappeared... this must mean that CaCO3 is no
more left and git converted into something.