F.4 Redox Reactions
Please do no.6 and no. 10 which show on the following webpage.
- 老爺子Lv 71 decade agoFavorite Answer
Yes, I agree.
When green chlorine gas is bubbled into the colourless solution, the solution changes to brown.
Cl2(g) + 2e- → 2Cl-(aq)
Chlorine is reduced. The oxidation number of Cl decreases from 0 (in Cl2) to -1 (in Cl-).
2Br-(aq) → Br2(aq) + 2e-
Chlorine is more reactive (a stronger oxidizing agent) than bromine. Therefore, chlorine can oxidize bromide ion to bromine.
The reaction undergoes in an acidic solution. Therefore, the potassium manganate(VII) solution (or the iron(II) solution) should be acidified.
On addition of the manganate(VII) solution to the iron(II) solution, the purple mangnate(VII) solution is decolorized and the pale green iron(II) changes to yellow gradually. At the end point, the solution changes from yellow to pale pink.
The reducing agent is the iron(II) ion.
When all iron(II) had reacted, further addition of manganate(VII) caused no reaction. A slightly excess of manganate(VI) solution made the solution change to pale pink.
MnO4-(aq) + 8H+(aq) + 5e- → Mn2+(aq) + 4H2O(l)
Fe2+(aq) → Fe3+(aq) + e-