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Tests for Unit 2!
The Reducing Ability of the Halide Ions
The reducing ability of the halide ions increases as we go down the group. We can test this by
reacting the halide ions with concentrated sulphuric acid:
This is an acid-base reaction. No reduction has taken place.
This is the same acid-base reaction, but the HBr then reduces more sulphuric acid.
Because Bromine is a better reducing agent, it then reduces the sulphuric acid to sulphur
dioxide, bromine and water.
Again, this reaction occurs, which then further reduces sulphuric acid.
But then this is reduced further and two other reactions take place, to form hydrogen sulphide