Question 4
Carbon and its CompoundsBubbling of CO2 into Ca(OH)2(aq) a white precipitate is formed. In the presence of carbon dioxide (in excess) the white precipitate disappears. The reason for this is
- A.calcium hydrogen carbonate is precipitated and then dissolve
- B.calcium carbonate is formed which on reaction dissolves
- C.concentration of the solution has occurred with the deposition of calcium hydroxide
- D.calcium carbonate is formed which on reaction with further carbondioxide forms soluble calcium hydrogen carbonate
Show the answer and explanation
Answer: D (calcium carbonate is formed which on reaction with further carbondioxide forms soluble calcium hydrogen carbonate)
Explanation
CO2 first gives insoluble CaCO3 (milky); excess CO2 and water turn it into soluble Ca(HCO3)2, so the precipitate clears.