balance half equations in basic solution

Question

ClO3- to ClO4-
Zn to zn2+
BrO3- to Br-
IO3- to I2
Sn2+ to Sn4+

Answer 1

Here are the rules.
http://www.chemteam.info/Redox/Redox.html

The first one as an example of how these are applied.
ClO3^- ==> ClO4^-

1. Oxidation state Cl on left is +5; on the right is +7. Add electrons to the appropriate side to balance the change in oxdn state.
ClO3^- ==> ClO4^- + 2e

2. Count the charge on the left and right and balance by adding either
a)H+ in acid solution or
b)OH^- in basic solution.
I see -1 charge on left and -3 on right; therefore,
ClO3^- + 2OH^- ==> ClO4^- + 2e

3. Now add H2O to the appropriate side to balance H (and O).
ClO3^- + 2OH^- ==> ClO4^- + 2e + H2O

4. check it for
a. atoms balance
b. charge balance
c. change in oxidation state balance.

If you have any questions about this or the others, please post your work and explain in detail exactly what trouble you are having. These are simple enough if you follow the rules. By the way, your question would have been answered quicker if you had not changed your screen name for your posts. It helps us help you if you use the same screen name.