Question

what happens when excess of CO2 is passed through slaked lime . Give the required chemical reaction

Answer 1

Wen CO2 is made to pass thro lime water, the lime water is observed to turn milky ; the formation of calcium carbonate makes it look milky
Ca(OH)2 + CO2 —-> CaCO3 + H2O

But when more of CO2 is added, a soluble substance called calcium bicarbonate is formed which will dissolve in the liquid and make it clear again

CaCO3+CO2+H2O—-> CaHCO3 + H2O

Answer 2

when CO2 is added to slaked lime(Ca(OH)2) we get ,white coating in walls called calcuim carbonate .this is used for white washing .when slaked lime are applied to walls within a day it will give a white layer limestone has the same constituite in it . 

Ca(OH)2+CO2=CaCo3+H20

when amount of CO2 is added to CaCO3 we get CaHCO3 and water 
CaCO3+CO2+H20=CaHCO3+H20