Question

When chlorine gas is bubbled into an aqueous solution of potassium iodide, the colourless solution turns brown.

i) Write an ionic equation for the reaction that takes place
ii) What is the name given to this type of reaction?
iii) Why does the solution turn brown?

Answer 1

(c) A redox reaction takes place when aqueous chlorine is added to potassium iodide solution. The equation for this reaction is: Cl2(aq) + 2KI(aq) → I2 (aq) + 2KCl(aq)

Answer 2

When chlorine (Cl 2 ) gas is passed through an aqueous solution of potassium iodide (KI), the products formed are solid iodine (I2) and potassium chloride (KCl). This is a displacement reaction in which the less reactive iodine in potassium iodide is displaced by the more reactive chlorine. The equation can be written as:

2KI(aq)+Cl2(g)→2KCl(aq)+I2 (s)