Join TSR now and get all your revision questions answeredSign up now

Why is the colour of chlorine water and potassium iodide solution brown?

    • Thread Starter

    Why is it brown

    In the water you have Cl2 molecules and I- ions.

    Chloride ions are more stable than iodide ions, so we have

    Cl2(aq) + 2I-(aq) ---> I2(aq) + 2Cl-(aq)

    Halide ions are colourless in water, so the colour you see is the iodine. Iodine is brown in aqueous solution, hence you see brown.
Which party will you be voting for in the General Election 2017?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.