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Directions to Determine Redox Reactions
1. Obtain a complete chemical reactions
2. Determine the OxidationNumber for each species in the reactants and products.
3. Looking at the OxidationNumber, determine the species that OxidationNumber have changed from reactant to product.
- Place one end of the bracket above the reactant species that has changed OxidationNumber and the other end of product species.
- One bracket above the chemical equation and one below.
If no species changes their Oxidation Number, it is not a Redox Reaction.
4. Write on the line of the bracket the reactant's OxidationNumber an arrow then the product's OxidationNumber. Determine if electrons are lost or gained.
- When the oxidation number becomes more negative (increases negative number or decrease positive number), the species is gaining electrons, it is being reduced. Write gain e- on the line.
- When the oxidation number becomes more positive (increase positive number or decrease negative number), the species is losing electrons, it is being oxidized. Write lose e- on the line.
- LEO the lion goes GER is how you remember what is oxidized and is reduced,
- LEO - Losing Electrons = Oxidation
- GER - Gaining Electrons = Reduction
- Remember, it is the species and not the whole compound that is being oxidized or reduced.
5. Determine the oxidizing agent and the reducing agent.
- Agent are the complete compound (or elements) not just the species.
- As discussed in Notes on Oxidation-Reduction Reactions, oxidizing agent "help" the species that oxidizes. So put your hand over the species that oxidizes and look to see what is written on opposite side of plus sign in chemical equation. That whole "thing" is the oxidizing agent.
- Do the same thing as above except replace oxidized with reduced to obtain the "reducding agent".
6. How to write the answer.
After showing above chemical equation with brackets etc., then answer goes below chemical equation
_____________ is reduced ____________ is reducing agent
_____________ is oxidized _____________ is oxidizing agent
- Always do the same thing since they are tied together.
- Remember, first column (substance oxidized/reduced) is a component of one of the reactants and the second columns (i.e. agents) are all the information between the plus signs.