Hydrocarbons: Practice Questions

Which statement best explains why cracking is a vital process in the petroleum industry?

A \(40\text{ cm}^3\) gaseous mixture of ethane (\(C_2H_6\)) and ethene (\(C_2H_4\)) is passed through a tube containing an excess of bromine dissolved in an organic solvent. The volume of the gas is found to decrease to \(15\text{ cm}^3\).

What is the total volume of oxygen required for the complete combustion of the original \(40\text{ cm}^3\) mixture? (All gas volumes are measured at room temperature and pressure.)

In the presence of ultraviolet light, methane reacts with chlorine. Which of the following species is not a possible product of the continued substitution of methane with excess chlorine?

The cracking of a long-chain alkane, \(\text{C}_{12}\text{H}_{26}\), produces one molecule of ethene, one molecule of propene, and one molecule of an unbranched alkane X. What is the name of alkane X?

Which of the following observations would correctly distinguish between a sample of liquid hex-1-ene and a sample of liquid hexane?

A sample of liquid propane and a sample of liquid octane are placed in separate open dishes at room temperature. State which compound evaporates faster and explain this difference in terms of intermolecular forces.

Industrial synthesis of ethanol involves the catalytic hydration of ethene. State the specific catalyst and temperature conditions used, and write a balanced chemical equation including state symbols for this reaction.

Describe the chemical test used to distinguish between a sample of ethane and a sample of ethene, and state the observation for each gas.

A student carries out investigations on two structural isomers of an alkene having the molecular formula \(\text{C}_4\text{H}_8\).

(a) Draw and name the two straight-chain positional isomers of \(\text{C}_4\text{H}_8\). (2 marks)
(b) Both isomers undergo an addition reaction with steam in the presence of concentrated \(\text{H}_3\text{PO}_4\) at \(300^\circ\text{C}\) and \(60\text{ atm}\).
(i) Name the single alcohol product formed from the symmetrical straight-chain isomer of \(\text{C}_4\text{H}_8\). (1 mark)
(ii) Draw the structural formula of this alcohol product. (1 mark)
(c) State the observation when an aqueous solution of bromine is added to either isomer in the dark. (1 mark)

Alkanes and alkenes are two important homologous series of hydrocarbons.

(a) Define the term homologous series and state two characteristics shared by members of the same series.
(b) Describe a chemical test to distinguish between a sample of ethane and a sample of ethene. Include the observation for each gas.
(c) When ethene reacts with steam in the presence of a catalyst, a product \(X\) is formed. Name product \(X\) and draw its full structural formula.