Hydrogen halides are made when halogens react with hydrogen. Describe and explain how the reactivity of the halogens changes down the group when they react with hydrogen to form HCl, HBr and HI.
HCl appears as a product in several separate reactions, some of which are illustrated in Fig. 3.1.
Write the chemical equation for reaction 1.
In reaction 2, NaCl reacts with concentrated $\text{H}_2\text{SO}_4$ to make HCl and $\text{NaHSO}_4$. When NaBr reacts with concentrated $\text{H}_2\text{SO}_4$, $\text{Br}_2$ and $\text{SO}_2$ are also formed. Use Table 3.1 to identify the reaction type(s) in each case, and explain why the reactions differ.
When warmed with a Bunsen burner, HCl remains unchanged, but HI gives $\mathrm{H_2}$ and $\mathrm{I_2}$. Explain why heating affects HCl and HI differently.
In water, the hydrogen halides produce strong Brønsted-Lowry acids. The concentration of a strong acid can be found by titration.
State what the term strong Brønsted-Lowry acid means.
On Fig. 3.2, draw the pH titration curves for: • $0.1\ \text{mol dm}^{-3}$ NaOH(aq) added to $25\ \text{cm}^3$ of $0.1\ \text{mol dm}^{-3}$ HBr(aq), until in excess. • $0.1\ \text{mol dm}^{-3}$ NH$_3$(aq) added to $25\ \text{cm}^3$ of $0.1\ \text{mol dm}^{-3}$ HBr(aq), until in excess.
Complete the diagram to show the mechanism for the reaction of HBr with propene to make the major organic product. Include charges, dipoles, lone pairs of electrons and curly arrows where needed. Draw the structures of the intermediate and the major organic product.
Explain why the two bromoalkanes are not formed in equal amounts by this reaction.
The reaction between $\text{CH}_3\text{CH}_2\text{CH}_2\text{Br}$ and $\text{NaOH}$ depends on whether water or ethanol is used as the solvent. Complete Table $3.2$ to name the organic and inorganic products formed when $\text{CH}_3\text{CH}_2\text{CH}_2\text{Br}$ reacts with $\text{NaOH}$ in each solvent.