question_answer 81)

    Look at the figure and answer the following questions. (a) What change would you observe in the calcium hydroxide solution taken in tube B? (b) Write the reaction involved in test tubes A and B respectively. (c) If ethanol is given instead of ethanoic acid, would you expect the same change? (d) How can a solution of lime water be prepared in the laboratory?

Answer:

                  (a) When CO2is passed through calcium hydroxide solution (taken in test tube B), i.e., limewater, it turns milky due to the formation of insoluble calcium carbonate (CaCO3) (b) Test tube A Test tube B (c) If ethanol is taken instead of ethanoic acid, no change will occur because ethanol is a very weak acid and hence cannot decompose  to give  gas. No reaction (d) When quick lime (CaO) is added to water in a test tube. Some of it will dissolve to form calcium hydroxide (lime water) while majority of it remains suspended. Filter the solution. The clear solution thus obtained is called lime water.