Home / AS & A Level Chemistry 11.2 The chemical properties of the halogen elements and the hydrogen halides Exam Style Practice Questions Paper 1
Equation 1 and equation 2 show two different reactions of halide ion \(Q^-\) with concentrated sulfuric acid.
Equation 1 \(\mathrm{H_2SO_4+Q^-\rightarrow HSO_4^-+HQ}\)
Equation 2 \(\mathrm{H_2SO_4+2Q^-+2H^+\rightarrow SO_2+Q_2+2H_2O}\)
What is \(Q\)?
Correct Answer: \( \boxed{\mathrm{B}} \)
Equation 1 is an acid-base reaction that occurs with all halide ions.
Equation 2 is a redox reaction in which concentrated sulfuric acid is reduced to \(\mathrm{SO_2}\) and the halide ions are oxidised to halogen molecules.
Bromide and iodide ions are sufficiently strong reducing agents to reduce concentrated sulfuric acid, whereas chloride ions are not.
Therefore, the correct answer is (B).
What happens when iodine solution is added to a solution of sodium bromide?
Correct Answer: \( \boxed{\mathrm{D}} \)
The reactivity of the halogens decreases down Group 17:
\(\mathrm{Cl_2>Br_2>I_2}\)
A more reactive halogen displaces a less reactive halide ion from solution.
Iodine is less reactive than bromine, so iodine cannot oxidise bromide ions.
Therefore, no reaction occurs and the correct answer is (D).
Which row is correct?
| property | explanation | |
|---|---|---|
| A | AgI dissolves in aqueous ammonia more readily than AgCl does | AgI reacts with aqueous ammonia |
| B | HCl decomposes more readily than HI does | Cl is more electronegative than I |
| C | \( \mathrm{I_2} \) has a higher melting point than \( \mathrm{Cl_2} \) | \( \mathrm{I_2} \) has stronger van der Waals’ forces than \( \mathrm{Cl_2} \) |
| D | \( \mathrm{I_2} \) is a stronger oxidising agent than \( \mathrm{Cl_2} \) | An I atom loses electrons more readily than a Cl atom |
Correct Answer: \( \boxed{\mathrm{C}} \)
Examine each row:
Therefore, the correct answer is (C).