CAPE Chemistry Unit 1 · 2012 · Paper 2 · Question 3(b)(iii)

A student was provided with three test tubes, EACH containing one hydrogen halide. A red hot wire (exceeding 300 °C) was quickly placed into each test tube in turn. The observations were recorded in Table 2. Test Tube I: Hydrogen chloride, No change. Test Tube II: Hydrogen bromide, Slight brown colouration seen. Test Tube III: Hydrogen iodide, Copious violet fumes seen.

Using the relevant information provided in the data booklet, explain the trend in the observations recorded in Table 2.

This question uses a figure or table from the paper — you'll see it when you practise.