The elements in Group 7 of the Periodic Table are known as the halogens.
Write a balanced chemical equation to show the formation of the salt potassium iodide from a metal and a halogen.
Hydrogen iodide, HI\text{HI}HI, can behave differently depending on the solvent.
When hydrogen iodide is dissolved in the non-polar solvent cyclohexane, and a piece of zinc ribbon is added, no reaction is observed. However, when water is added to this mixture and it is shaken, a reaction occurs.
Explain this observation, identifying the gas produced and why the reaction only proceeds after adding water.
Hydrogen iodide and hydriodic acid can both be represented by the formula HI\text{HI}HI. State the physical state symbol at room temperature for each:
Bromine can displace iodine from an aqueous solution of sodium iodide. The ionic half-equations for this reaction are: \
\text{Br}_2 + 2\text{e}^- \rightarrow 2\text{Br}^-{\char"24}$ \2\text{I}^- \rightarrow \text{I}_2 + 2\text{e}^-{\char"24}$
Write the overall balanced ionic equation for this displacement reaction.
Explain, with reference to the appropriate species and to electrons, why this reaction is described as a redox reaction.
33 exam-style questions on Edexcel IGCSE Chemistry Group 7 (halogens) – chlorine, bromine and iodine. Each one has a worked solution and a mark scheme showing where the marks go.