- Why does carbon form compounds mainly by covalent bonding?
- List any two reasons for carbon forming a very large number of compounds.
- An organic acid 'X' is a liquid which often freezes during winter time in cold countries, has the molecular formula C2H4O2. On warming it with ethanol in the presence of a few drops of concentrated sulphuric acid, a compound 'Y with a sweet smell is formed.
- Identify X and Y
- Write a chemical equation for the reaction involved.
(a) Carbon has 4 electrons in its valence shell. In order to attain stability, it can neither gain 4 electrons nor lose 4 electrons as losing 4 electrons involves a lot of energy. Also, it cannot gain 4 electrons because the nucleus cannot hold on to the four extra electrons added. Hence, to complete the octet, it shares 4 electrons with other atoms. This is why carbon forms compound mainly by covalent bonding.
(b) Catenation and tetravalency nature of carbon is the reason for the formation of a large number of compounds. The property of the formation of bonds with other carbon atoms to form long chains of different compounds is called catenation. Carbon has 4 electrons in its outermost orbit so it is a tetravalent compound.
(c) (i) The organic acid, X, which often freezes in the winters in cold countries, is ethanoic acid. It has the molecular formula CH3COOH. Y is methyl ethanoate. Its formula is CH3COOCH3.
(ii) The chemical equation is given below:
$CH_3COOH + CH_3OH \xrightarrow {conc. H_2SO_4} CH_3COOCH_3 + H_2O$.
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- An organic acid X is a liquid, which often freezes during winter time in cold countries, having the molecular formula C2H4O2. On warming it with methanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet smell is formed.(a) Identify X and Y. Also write their formulae showing the functional group present in them. (b) Write a chemical equation for the reaction involved.
- (a) What happens when ethanol reacts with ethanoic acid in the presence of a little of concentrated sulphuric acid? Write equation of the reaction involved.(b) What happens when ethanol is heated with concentrated sulphuric acid at 170°C? Write the equation of the reaction which takes place.
- (a) What is the general name of all the compounds made up of carbon and hydrogen?(b) Why does carbon form compounds mainly by covalent bonding?
- An organic compound A (molecular formula C2H4O2) reacts with Na metal to form a compound B and evolves a gas which burns with a pop sound. Compound A on treatment with an alcohol C in the presence of a little of concentrated sulphuric acid forms a sweet-smelling compound D (molecular formula C3H6O2). Compound D on treatment with NaOH solution gives back B and C. Identify A, B, C and D.
- A compound X is formed by the reaction of a carboxylic acid C2H4O2 and an alcohol in the presence of a few drops of H2SO4. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structures of (a) carboxylic acid, (b) alcohol and (c) the compound X. Also, write the reaction.
- A neutral organic compound X of molecular formula C2H6O on oxidation with acidified potassium dichromate gives an acidic compound Y. Compound X reacts with Y on warming in the presence of conc. H2SO4 to give a sweet smelling substance Z. What are X, Y, and Z?
- A four carbons atoms containing neutral organic compound X reacts with sodium metal to evolve a gas which burns with 'pop' sound. Another four carbon atoms containing carbon compound reacts with sodium hydrogen carbonate to evolve a gas which turns lime water milky. When compounds X and Y are heated together in the presence of a little of concentrated sulphuric acid, then a new compound Z is formed.(a) What is compound X ? Also write its formula. (b) What is compound Y ? Also write its formula. (c) What is compound Z ? Also write its formula. (d) What type of smell is given by compound Z? (e) What is the general name of compounds like Z? (f) What is the general name of the reaction which takes place between X and Y to form Z?
- A compound 'X' on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound 'Y'. 'X ' also reacts with sodium metal to evolve a colorless gas 'Z'. Identify 'X ', 'Y' and 'Z'. Write the equation of the chemical reaction of formation of 'Y', and also write the role of sulphuric acid in the reaction.
- Ethene is formed when ethanol at 443 K is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction? Write the balanced chemical equation of this reaction.
- Write chemical equations to show what happens when:i. Ethanol is heated with concentrated sulphuric acid at 443 K.ii. Ethanol reacts with ethanoic acid in the presence of an acid acting as a catalyst.iii. An ester reacts with a base.
- (a) Why does the element carbon form a large number of carbon compounds?(b) Write down the structures and names of two isomers of butane (C4H10).
- Hydrochloric acid reacts with a metal X to form a gas Y which burns with a ‘pop’ sound. Sodium hydroxide solution also reacts with the same metal X (on heating) to form the same gas Y.(a) Name X and Y(b) Write the chemical equation of the reaction of metal X with (i) Hydrochloric acid, and (ii) Sodium hydroxide solution.
- (a) What happens when propanoic acid is warmed with methanol in the presence of a few drops of concentrated sulphuric acid? Write equation of the reaction involved.(b) What change will you observe if you test soap solution with a litmus paper (red and blue)? Give reason for your observation.(c) What is meant by denatured alcohol? What is the need to denature alcohol?
- A compound C (molecular formula, C2H4O2 ) reacts with Na – metal to form a compound R and evolves a gas which burns with a pop sound. Compound C on treatment with an alcohol A in presence of an acid forms a sweet-smelling compound S (molecular formula, C3H6O2 ). On addition of NaOH to C, it also gives R and water. S on treatment with NaOH solution gives back R and A. Identify C, R, A, S and write down the reactions involved.
- (a) What happens when an acid reacts with a metal? Give chemical equation of the reaction involved.(b) Which gas is usually liberated when an acid reacts with a metal? How will you test for the presence of this gas?
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