(a) Methane reacts with chlorine under certain condition to produce tetrachloromethane.
(i) State the condition for the reaction
(ii) Name the type of reaction
(iii) Give two uses of methane
(iv) Name one major natural source of methane
(b)(i) Mention one similarity between the reaction of ethanol with sodium and that of sodium with water
(ii) Write the structure of two isomers of C\(_3\)H\(_8\)O
(iii) Differentiate between a fine chemical and a heavy chemical
(iv) Give one example of each in (b)(iii) above
(c) Two compounds X and Y have the same percentage composition by mass of 92.3% carbon and 7.7% hydrogen. Calculate the:
(i) empirical formula of X and Y;
(ii) molecular formula of each compound if molar mass of X is 26 g and Y is 78g.
(d) A protein is boiled for a long time with dilute HCI and a reaction occurred.
(i) State the type of reaction that occurred
(ii) Name the major product formed
(iii) Give the functional groups present in (d)(ii) above.
(a)(i) Condition: presence of (ultraviolet) sunlight / diffused light.
(ii) Type of reaction: substitution (photochemical, free-radical substitution).
(iii) Uses of methane: as a domestic and industrial fuel (natural gas); manufacture of hydrogen; manufacture of carbon black / methanol.
(iv) Major natural source: natural gas (also biogas/marsh gas from decaying organic matter).
(b)(i) Similarity: both reactions liberate hydrogen gas. (\(2Na + 2C_2H_5OH \rightarrow 2C_2H_5ONa + H_2\); \(2Na + 2H_2O \rightarrow 2NaOH + H_2\)).
(ii) Two isomers of C3H8O
Propan-1-ol: CH3-CH2-CH2-OH
Propan-2-ol: CH3-CH(OH)-CH3
(iii) A fine chemical is made in small quantities to a high degree of purity and is costly; a heavy chemical is made in large (bulk) quantities and is of lower purity.
(iv) Fine chemical: a drug (for example aspirin) or a dye. Heavy chemical: tetraoxosulphate(VI) acid (or sodium hydroxide, ammonia).
(c) C : H by mass = 92.3% : 7.7%.
C: \(\dfrac{92.3}{12} = 7.69\); H: \(\dfrac{7.7}{1} = 7.7\). Ratio \(\approx 1:1\).
(i) Empirical formula of X and Y = CH (empirical mass = 13).
(ii) X: \(\dfrac{26}{13} = 2\), so molecular formula = C2H2 (ethyne). Y: \(\dfrac{78}{13} = 6\), so molecular formula = C6H6 (benzene).
(d)(i) Type of reaction: hydrolysis.
(ii) Major product: amino acids.
(iii) Functional groups present: the amino group (-NH2) and the carboxyl group (-COOH).
(a)(i) Condition: presence of (ultraviolet) sunlight / diffused light.
(ii) Type of reaction: substitution (photochemical, free-radical substitution).
(iii) Uses of methane: as a domestic and industrial fuel (natural gas); manufacture of hydrogen; manufacture of carbon black / methanol.
(iv) Major natural source: natural gas (also biogas/marsh gas from decaying organic matter).
(b)(i) Similarity: both reactions liberate hydrogen gas. (\(2Na + 2C_2H_5OH \rightarrow 2C_2H_5ONa + H_2\); \(2Na + 2H_2O \rightarrow 2NaOH + H_2\)).
(ii) Two isomers of C3H8O
Propan-1-ol: CH3-CH2-CH2-OH
Propan-2-ol: CH3-CH(OH)-CH3
(iii) A fine chemical is made in small quantities to a high degree of purity and is costly; a heavy chemical is made in large (bulk) quantities and is of lower purity.
(iv) Fine chemical: a drug (for example aspirin) or a dye. Heavy chemical: tetraoxosulphate(VI) acid (or sodium hydroxide, ammonia).
(c) C : H by mass = 92.3% : 7.7%.
C: \(\dfrac{92.3}{12} = 7.69\); H: \(\dfrac{7.7}{1} = 7.7\). Ratio \(\approx 1:1\).
(i) Empirical formula of X and Y = CH (empirical mass = 13).
(ii) X: \(\dfrac{26}{13} = 2\), so molecular formula = C2H2 (ethyne). Y: \(\dfrac{78}{13} = 6\), so molecular formula = C6H6 (benzene).
(d)(i) Type of reaction: hydrolysis.
(ii) Major product: amino acids.
(iii) Functional groups present: the amino group (-NH2) and the carboxyl group (-COOH).
