Draw and name the isomers of pentane. (b) Ethane gas was reacted with 1 mole of bromine gas. State one observation made during this reaction.

Here are the answers to your questions:

31. (a)
The isomers of pentane ($\text{C}_5\text{H}_{12}$) are:

1. Pentane (or n-pentane) $$\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3$$
2. 2-Methylbutane (or isopentane) $$\text{CH}_3-\text{CH}(\text{CH}_3)-\text{CH}_2-\text{CH}_3$$
3. 2,2-Dimethylpropane (or neopentane) $$\begin{matrix} & \text{CH}_3 \\ & | \\ \text{CH}_3 & - & \text{C} & - & \text{CH}_3 \\ & | \\ & \text{CH}_3 \end{matrix}$$

31. (b)
When ethane gas reacts with 1 mole of bromine gas, the observation made is that the reddish-brown color of bromine disappears.

32.

• (a) Identify:
  • (i) X: Ethene ($\text{C}_2\text{H}_4$)
  • (ii) Y: Chloroethene (or Vinyl chloride, $\text{CH}_2=\text{CHCl}$)
• (b) State two uses of polyvinylchloride.
  1. Manufacturing of pipes and fittings.
  2. Insulation for electrical cables.

33. (a)
The purpose of the sand was to act as a catalyst and provide a large surface area for the cracking reaction.

33. (b)
Gas G is an alkene.

• Chemical test: Add bromine water to gas G.
• Observation: The reddish-brown color of the bromine water disappears.

34. (a)
When excess pentene is reacted with bromine gas, the observation made is that the reddish-brown color of the bromine gas disappears.

34. (b)
The compound formed is 1,2-Dibromopentane (assuming pent-1-ene).