Q53 of 60 Page 36

Look at figure given below 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?


(a) Calcium hydroxide solution will turn milky.

(b) 2CH3COOH + Na2CO3→ 2CH3COONa + H2O + CO2 (Test tube A)

Ca(OH)2 + CO2→ CaCO3 + H2O (Test tube B)

The white colour of the liquid disappears with excess CO2.

CaCO3 + H2O + CO2→ Ca(HCO2)2

(c) Ethanol (C2H5OH) does not react with sodium carbonate (Na2CO3). Hence no similar reaction takes place.

(d) For preparing lime water in the laboratory, calcium oxide (quick lime) is dissolved in water and the mixture is allowed to settle. The supernatant liquid is then decanted lime water is obatined.

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