Draw the structural formula of X, name reaction 1 and 2, name the type of elimination reaction 3 and give the condensed formula of product Z.

Here are the solutions to the questions:

3.1 Consider reaction 1:

3.1.1 X is the major product formed. Draw the structural formula of X.
Reaction 1 is a nucleophilic substitution reaction where the bromine atom in 2-bromobutane is replaced by a hydroxyl group from dilute NaOH, forming butan-2-ol.

$$\begin{align*} &\quad H \quad H \quad H \quad H \\ &\quad | \quad | \quad | \quad | \\ H & - C - C - C - C - H \\ &\quad | \quad | \quad | \quad | \\ &\quad H \quad OH \quad H \quad H \end{align*}$$

3.1.2 Name the type of reaction.

• Nucleophilic substitution

3.2 Consider reaction 2:

3.2.1 Draw the structural formula of the major product, Y.
Reaction 2 is an elimination reaction (dehydrohalogenation) using concentrated NaOH in hot ethanol. The bromine atom and a hydrogen atom from an adjacent carbon are removed to form an alkene. According to Zaitsev's rule, the major product is the more substituted alkene, which is but-2-ene.

$$\begin{align*} &\quad H \quad H \quad H \quad H \\ &\quad | \quad | \quad | \quad | \\ H & - C - C = C - C - H \\ &\quad | \quad \quad \quad | \\ &\quad H \quad \quad \quad H \end{align*}$$

3.2.2 Name the type of reaction.

• Elimination

3.3 Consider reaction 3:

3.3.1 Name the type of elimination reaction.

• Cracking

3.3.2 Give the condensed formula of product Z.
The reactant is hexane ($C_6H_{14}$). The products are ethene ($C_2H_4$) and ethane ($C_2H_6$).
To find Z, we subtract the atoms of ethene and ethane from hexane:
$C_6H_{14} - (C_2H_4 + C_2H_6) = C_6H_{14} - C_4H_{10} = C_2H_4$.
The condensed formula for $C_2H_4$ is $CH_2=CH_2$.

• $\boxed{CH_2=CH_2}$

3.4 Compound Z is a monomer of a polymer used to make plastic bags:

3.4.1 Write down the NAME and CONDENSED STRUCTURAL FORMULA of this polymer.
Compound Z is ethene. The polymer formed from ethene is poly(ethene) or polyethylene.

• Name: Poly(ethene) (or Polyethylene)
• Condensed structural formula: $\boxed{-(CH_2-CH_2)_n-}$

3.4.2 Describe the type of polymerisation that forms the polymer in QUESTION 3.4.1.

• Addition polymerisation