Question

Look at below figure and answer the following questions.

1.  What change would you observe in the calcium hydroxide solution taken in tube B?
2. Write the reaction involved in test tubes A and B respectively.
3. If ethanol is given instead of ethanoic acid, would you expect the same change?
4. How can a solution of lime water be prepared in the laboratory?

Answer 1

1. Calcium hydroxide solution taken in tube B becomes milky because of the formation of calcium carbonate.
2. In test tube A, ethanoic acid reacts with sodium carbonate to give sodium acetate, water, carbon dioxide. 
   \[\ce{2CH3COOH  + Na2CO3 -> 2CH3COONa + H2O + CO2}\]
   In test tube B, when carbon dioxide is passed through lime water, it turns milky.
   \[\ce{Ca(OH)2 + CO2 -> CaCO3 + H2O}\]
3. If ethanol is given instead of ethanoic acid, the same change would not be expected because ethanol does not react with sodium carbonate.
4. Lime water is obtained on dissolving quick lime in water. A lot of heat is produced in this reaction.
   \[\ce{CaO + H2O -> Ca(OH)2 + Heat}\]