JAMB - Chemistry (2002 - No. 37)
A rock sample was added to cold dilute HNO3. The gas evolved was passed into a solution of acidified K2Cr2O7 and the solution turned green. The sample contains
Cl-
NO3-
SO32-
SO42-
Uitleg
Sulphur dioxide reacts with potassium dichromate and sulphuric acid to produce potassium sulphqqqqqqqqqqqqqqqate, chromium(III) sulfate and water and the solution turns from orange to green.