Chemistry
(i) Give a chemical test to distinguish ethene gas and ethane gas.
(ii) Identify the statement that is incorrect about alkanes:
(A) They are hydrocarbons.
(B) There is a single covalent bond between carbon and hydrogen.
(C) They can undergo both substitution as well as addition reactions.
(D) On complete combustion they produce carbon dioxide and water.
Answer
(i) When bromine is passed through solutions of each of the gases in an inert solvent [CCl4] at room temperature, incase of ethene gas, brown colour of bromine is discharged whereas in case of ethane gas brown colour remains brown.
(ii) They can undergo both substitution as well as addition reactions.
Reason — The non availability of electrons in the single covalent bond makes them less reactive and therefore alkanes undergo characteristic substitution reactions only.
Related Questions
A compound X when treated with an organic acid Y (having vinegar like smell) in the presence of the acid Z, forms a compound P which has a fruity smell.
(a) Identify X, Y and Z.
(b) Write structural formula of X and Y.
(c) What type of compound is P?
(d) Name the above reaction.
(e) If compound X and Y both have 2 carbon atoms. Write the reaction.
Compound A is bubbled through bromine dissolved in carbon tetrachloride and the product formed is CH2Br–CH2Br.
(i) Draw the structural formula of A.
(ii) What type of reaction has A undergone.
(iii) What is your observation.
(iv) Name (not formula) the compound formed when steam reacts with A in the presence of phosphoric acid.
(v) What is the procedure for converting the product of (e) (iv) back to A ?
Draw the structural formula for each of the following—
(a) Ethanoic acid
(b) But-2-yne
(c) Methanoic acid
(d) Ethanal
(e) Ethyne
(f) Acetone
(g) 2-methyl propane
(h) An isomer of n-butane
(i) 2-propanol
(j) ethanol
(k) 1-propanal
(l) ethanoic acid
(m) 1,2, dichloroethane
Give balanced chemical equation for the following conversions :
(a) Ethanoic acid to ethyl ethanoate.
(b) Calcium carbide to ethyne
(c) Sodium ethanoate to methane.
(d) Ethyl chloride to ethyl alcohol
(e) Ethyl chloride to ethene
(f) Ethene to ethyl alcohol
(g) Ethyl alcohol to ethene