Saturated hydrocarbons are fairly unreactive. But in the presence of sunlight, chlorine substitutes hydrogen one by one.

CH₄ + Cl₂ → CH₃Cl + HCl (in the presence of sunlight) 

This substitution can go on till, carbon tetrachloride is obtained.

When ester is treated with an alkali, the reaction gives ethanol and sodium ethanoate. This reaction is called saponification reaction because this reaction forms the basis of preparation of soap. This can be given by following equation. 

CH₃COOC₂H₅  + NaOH → CH₃COONa + C₂H₅OH

 

 

When a substance burns in the presence of oxygen, the reaction is called combustion. Following is an example of combustion reaction.

CH₄ + O₂ →CO+ H₂O + heat and light

 

 

(a) What change would you observe in the calcium hydroxide solution taken in tube B?
Ans. Calcium hydroxide solution in the test tube B becomes milky.
(b) Write the reaction involved in test tubes A and B respectively.
Ans. Reaction in test tube A:

CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O

Reaction in test tube B:
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

(c) If ethanol is given instead of ethanoic acid, would you expect the same change?
Ans. Ethanol does not react with sodium hydrogen carbonate. Hence, same change cannot be observed.

(d) How can a solution of lime water be prepared in the laboratory?
Ans. For this, take distilled water in a beaker and mix calcium carbonate powder in it. After stirring thoroughly, wait till the mixture settles. Decant the clear liquid from the beaker. This liquid is lime water.

(a) ethanol to ethene. Ans. Ethanol is heated at 443 k in the presence of excess of conc. sulphuric acid. This reaction is called dehydrogenation. This reaction can be given by following equation:

(b) propanol to propanoic acid. Ans. Propanol is treated with alkaline potassium permanganate or acidified potassium dichromate to obtain propanoic acid.

Following are the isomers of this compound.

Following is the electron dot structure: