Question

what happen when lime add in h20

Answer 1

CaCO3 is nearly insoluble in water. But when it dissolve in water, the little amount of CaCO3 that has been dissolved gives the following products

CaCO3(aq){means CaCO3 +H2O}= Ca2+(aq ) + CO3 2-(aq)

Now the CO3 2- picks up two protons from water and converted to H2CO3 (very weak acid) which is very unstable and break down to form CO2 and H2O.

So when CaCO3 is dissolved in water CO2 is evolved as bubbles.