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प्रश्न
Esters are sweet-smelling substances and are used in making perfumes. Describe an activity for the preparation of an ester with the help of a well labelled diagram. Write an equation for the chemical reaction involved in the formation of the ester. Also write the names of all the substances involved in the process of esterification.
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उत्तर
Esters are sweet-smelling substances which are used to make perfumes. The process in which a carboxylic acid reacts with an alcohol to form an ester is called esterification.
An ester is formed when ethanol (alcohol) reacts with ethanoic acid, on heating, in the presence of a few drops of concentrated sulphuric acid. The name of the ester formed is ethyl ethanoate.
Let's prepare an ester.
(1) In a test tube, take 1 ml of ethanoic acid and add some ethanol to it along with a few drops of concentrated sulphuric acid.
(2) Warm the test tube in a beaker, containing hot water, for 5 minutes.
(3) Take about 50 ml of water in another beaker and pour the contents of the test tube into it. When you smell it, a sweet fragrance is obtained indicating the formation of an ester.
The diagrammatic representation of the above process is as follows:
The chemical equation involved in the formation of ester is as follows:
`CH_3 COOH + C_2 H_5 OH` 
`CH_3 COOC_2 H_5 + H_2 O`
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संबंधित प्रश्न
The molecular formula of acetic acid is _________ .
(a) CH3COOH
(b) CH3 – CH3
(c) C6H6
(d) C2H4
For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?
(a) Castor oil and calcium hydroxide
(b) Turpentine oil and sodium hydroxide
(c) Castor oil and sodium hydroxide
(d) Mustard oil and calcium hydroxide
A student takes about 6 ml of distilled water in each of the four test tubes P, Q, R and S. He then dissolves an equal amount of four different salts namely, sodium chloride in 'P', potassium chloride in 'Q', calcium chloride in 'R' and magnesium chloride in 'S'. Next, he then adds 10 drops of soap solution to each test tube and shakes its contents. The test tubes in which scum (insoluble substance) is formed with soap are:
(A) P and Q
(B) Q and R
(C) R and S
(D) Q and S
You have four test tubes, A, B, C and D containing sodium carbonate, sodium chloride, lime water and blue litmus solutions respectively. Out of these the material of which test tube/ test tubes would be suitable for the correct test of acetic/ethanoic acid?
(a) only A
(b) A and B
(c) B and C
(d) A and D
When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?
(A) No reaction takes place
(B) A colourless gas with pungent smell is released with brisk effervescence
(C) A brown coloured gas is released with brisk effervescence
(D) Formation of bubbles of a colourless and odourless gas
When zinc powder is added to acetic acid ______________
(a) the mixture becomes warm
(b) a gas is evolved
(c) the colour of the mixture becomes yellow
(d) a solid settles at the bottom
What is the common name of methanoic acid.
What is the common name of methanol?
Which of the following will give brisk effervescence with sodium hydrogen carbonate and why?
CH3COOH, CH3CH2OH
Describe a test for carboxylic acid.
How would you distinguish experimentally between an alcohol and carboxylic acid on the basis of a chemical property?
What type of compound is formed when a carboxylic acid reacts with an alcohol in the presence of conc. H2SO4?
Name two oxidising agents which can oxidise ethanol to ethanoic acid.
How does ethanoic acid react with sodium hydrogen carbonate? Give equation of the reaction which takes place.
What do you notice when acetic acid reacts with metals?
Give two tests to show that CH3COOH is acidic in nature ?
While studying saponification reactions, the following comments were noted down by the students :
(I) Soap is a salt of fatty acids.
(II) The reaction mixture is basic in nature.
(III) In this reaction heat is absorbed.
(IV) This reaction is not a neutralisation reaction.
Which of these are the correct comments ?
(A) I and III only
(B) I, II and III
(C) II, III and IV
(D) I and II only
In an experiment to study the properties of acetic acid a student takes about 2 mL of acetic acid in a dry test tube. He adds about 2 mL of water to it and shakes the test tube well. He is likely to observe that:
(A) the acetic acid dissolves readily in water
(B) the solution becomes light orange
(C) water floats over the surface of acetic acid
(D) acetic acid floats over the surface of water
Write a balanced chemical equation for the following:
Monochloroethane is hydrolysed with aqueous KOH.
Give a chemical reaction in which a catalyst is used.
