Halogen Displacement & Redox Flashcards

All 6 cards in this deck

What is a halogen displacement reaction?

A more reactive halogen takes the place of a less reactive halogen in a solution of its halide.

What is seen when chlorine water is added to colourless potassium bromide solution?

The colourless solution turns yellow / orange / brown, as bromine is displaced.

What are the steps to write the ionic equation for a halogen displacement reaction?
e.g. chlorine water added to sodium bromide solution

1. Write the halogen and the halide ions as reactants: $\mathrm{Cl_2} + 2\mathrm{Br^-}$
2. The halogen becomes halide ions and the halide ions become a halogen molecule: $\rightarrow 2\mathrm{Cl^-} + \mathrm{Br_2}$
3. Check the balancing: $\mathrm{Cl_2} + 2\mathrm{Br^-} \rightarrow 2\mathrm{Cl^-} + \mathrm{Br_2}$

What is the half equation for the formation of bromine from bromide ions?

$2\mathrm{Br^-} \rightarrow \mathrm{Br_2} + 2\mathrm{e^-}$

In a halogen displacement reaction, which species is oxidised and which is reduced?

The halide ions are oxidised (lose electrons); the halogen is reduced (gains electrons).

True or false? Iodine displaces chlorine from potassium chloride solution.

False. Iodine is less reactive than chlorine, so no reaction occurs.