Based on the oxidation numbers which compound is the oxidizing agent in the following reaction?

8Al + 3KClO4 �¨ 4Al2O3 + 3KCl

2 answers

Calculate the oxidation numbers for each one

Elements all by themselves have an oxidation state of 0

Oxidation states for metals is usually the same as when they are an ion

For elements such as oxygen and hydrogen, their oxidation numbers correspond to the number of electrons they wish to lose or gain to have perfect octets

If you can figure out which atoms had their oxidation numbers changed you can find the oxidizing agent

Also remember Leoger

Loss of electrons is oxidation and gain of electrons is reduction

Your oxidizing agent is the element that gained electrons
Add this site to what Ally has written.
http://www.chemteam.info/Redox/Redox.html