Question #8340d

1 Answer
Jan 15, 2015

Both examples are redox reactions.

Let's take the general form of the first one (I'm not going to write the ions for Ba(OH)2, I'll just leave it like this):

Ba(OH)2(aq)+H2O2(aq)+2ClO2(aq)Ba(ClO2)2(s)+2H2O(l)+O2(g)

If you assign oxidation numbers to all the atoms involved in the reaction, you'll get

Ba+2(O2H+1)2+H+12O12+2Cl+4O22Ba+2(Cl+3O22)2+2H+12O2+O02

So, Cl's oxidation number changes from +4 in ClO2, to +3 in Ba(ClO2)2, while O's oxidation nubmer changes from -1 in H2O2, to 0 in O2.

Cl+4+1eCl+3
O1O0+1e

For the second reaction, you'll have

I+52O25+5C+2O2I02+5C+4O22

Iodine's oxidation number changes from +5 in I2O5, to 0 in I2, while carbon's oxidation number changes from +2 in CO, to +4 in CO2.

C+2C+4+2e
I+5+5eI0