Answer : Al
Explanation :
- For a given redox reaction there must be an oxidizing agent/(s) and a reducing agent/(s).
- the oxidizing agent is the substance that undergoes reduction process (gaining electrons or loss of oxygen atoms), meanwhile, the reducing agent is the substance that undergoes oxidation process (loss of electrons or gaining of oxygen atoms).
- In the reaction above, the oxidation number of (Al) in AlCl3 is (3+). However, the oxidation number of (Al) in the products is zero because it exists as a single element.
Therefore, changing from (3+) to zero means gaining of (3) electrons to neutralize the previously existing (3) protons on (Al) in AlCl3.
So Al is the oxidizing agent..