Question

Look at figure given below and answer the following questions-

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

Answer 1

Hint: This question is based on the two reactions taking place in two different test tube i.e. A and B. In test tube A, Reaction is taking place between sodium carbonate which has the chemical formula \[N{a_2}C{O_3}\] with ethanoic acid with chemical formula \[C{H_3}COOH\] . On the other hand, test tube B contains calcium hydroxide \[Ca{(OH)_2}\] solution.

Complete answer:
(a).The changes that occurs in test tube B i.e. calcium hydroxide solution \[Ca{(OH)_2}\] is that it turns milky as it forms calcium carbonate \[(CaC{O_3})\]due to the carbon dioxide \[(C{O_2})\] gas passing through it. The carbon dioxide \[(C{O_2})\] gas is released due to the reaction occurring in test tube A.
Reaction that occur:
\[Ca{(OH)_2}\,(aq)\, + \,C{O_2}\, \to CaC{O_3}\,(s)\, + {H_2}O\,(l)\]
(b).The following reactions that take place in both the test tube are:
Reaction involved in test tube A is as follows:
\[C{H_3}COOH\, + N{a_2}C{O_3} \to C{H_3}COONa + C{O_2} + {H_2}O\]
Reaction involved in test tube B is as follows:
\[Ca{(OH)_2}\,(aq)\, + \,C{O_2}\, \to CaC{O_3}\,(s)\, + {H_2}O\,(l)\]
(c).If ethanol is given instead of ethanoic acids, there will be no change observed.
\[C{H_3}C{H_2}OH\, + N{a_2}C{O_3} \to NO\,\,REACTION\]
(d).Preparation of solution of lime water in the laboratory
Take a small piece of calcium oxide \[(CaO)\] in a test tube. Add some water to it, some part of the calcium oxide gets dissolved and some gets suspended. Filter the complete solution with the help of filter and collect in a test tube. Hence, the solution prepared is lime water.
Reaction that occur-
\[CaO\, + {H_2}O\, \to \,Ca{(OH)_2}\]

Note:
It must be remembered that the calcium oxide \[(CaO)\] is commonly known as quicklime or burnt lime. The term ‘lime’ denotes calcium containing inorganic materials. Similarly, the common name of calcium hydroxide \[\,(Ca{(OH)_2})\] is slaked lime and for sodium carbonate \[(N{a_2}C{O_3})\] is washing soda or soda ash. You must remember these common names.