There is a very special way to tell if a reaction is an oxidation-reduction reaction, also known as a redox reaction.

All oxidation-reduction reactions contain ions that change their charges. If an ion in the reactant loses electrons (becomes a more positively charged ion in the product), the ion is said to be oxidized—that’s the oxidation portion of the reaction.

If an ion in the reactant gains electrons (becomes a more negatively charged ion in the product), the ion is said to be reduced. That part of the reaction is called reduction.

Here is a mnemonic device to help you remember the difference between oxidizing and reducting.

Directions

1. Use your notes to record your observations for the following activity.
2. For the questions listed below, find the oxidizing portion and the reducing portion of each reaction.
3. Record your answers in your notes.
   
   

Questions

1. Mg + O₂ → MgO

   After recording the oxidizing portion and reducing portion of the reaction, Interactive popup. Assistance may be required. Check Your Answer Oxidizing Portion
   Mg → Mg²⁺ because it loses 2e^- or Mg → Mg²⁺ + 2e^-
   Reducing Portion
   O₂→ O^2- because it gained 2e^- or O₂ + 2e^-→ O^2-

2. Cl₂ + I^-→ Cl^- + I₂

   After recording the oxidizing portion and reducing portion of the reaction, Interactive popup. Assistance may be required. Check Your Answer Oxidizing Portion
   I^-→ I₂ because it loses 1e^- or I^-→ I₂ + e^-
   Reducing Portion
   Cl₂→ Cl^- because it gained 1e^- or Cl₂ + e^-→ Cl^-

3. Fe²⁺ + MnO₄^-→ Mn²⁺ + Fe³⁺

   After recording the oxidizing portion and reducing portion of the reaction, Interactive popup. Assistance may be required. Check Your Answer Oxidizing Portion
   Fe²⁺→ Fe³⁺ because it loses 1e^- or Fe²⁺→ Fe³⁺ + e^-
   Reducing Portion
   MnO₄^-→ Mn²⁺ because it gained 5e^- or MnO₄^- + 5e^-→ Mn²⁺