A tutor’s guide on teaching about oxidation-reduction problems

By Stephanie Yan, Jennifer Zhang, and Farnaz Dayani

Key concepts

understand terminology

Understand general trends in oxidation states of various elements

understand concept of valence electrons and that valence electrons does NOT always correspond with oxidation number

Student's difficulty

Student is able to understand redox reactions with oxygen and hydrogen, but has difficulty with ones that don't only involve O2- and H+

Student sometimes gets confused with words like "oxidation reaction, oxidized element, and oxidizing agent”

student has not yet learned to balance redox equations

First, make sure the student understands that:

oxidation means gain of oxygen or loss of electrons

reduction invovles loss of oxygen or gain of electrons

Show a problem that includes gain or loss of oxygen

Show solution

reduction: CuO gets reduced

CuO+ H2 Cu + H2O(loss of “o”)

gaining oxygen, SO3(2-) gets oxidized ,SO3(2-) + H2O= SO4(2-)(gain of “o”)

Show a problem that does not involves loss or gain of oxygen

Show solution

EX: Zn + CuSO4= ZnSO4 + Cu

Zn(0) – 2e- -------Zn2+ lose electron, gets oxidized

CU2+ 2e- --------CU(0) gain electron, gets reduced, occurs reduction

In solution, include that the element that is reduced is the oxidizing agent and the element that is oxidized is the reducing agent

explain oxidation state and numbers (O is always 2-, H is usually +1, figure rest out from total compound/molecule's charge

Explain how to solve for an element’s oxidation states in absence of O2- and H+

use boxes with arrows and letters up/down O(r)R(a), down/up R(r)O(a)

Love story between Mr. Orra and Ms. Rroa and flowers are e-

you cannot marry yourself/ be a husband-wife so you can't be the oxidizing agent AND be oxidized. Therefore if you are oxidized, you are the reducing agent.

↑ ↓ O R

↓ ↑ R O

O.S Electron Reaction Agent

LEO the lion says GER (can also be visual verbal)

Lose Electron = Oxidation

Gain Electron = Reduction

When you gain an electron, the charge is actually reduced because electrons are negative charge

Story telling along with previous example of love story (once upon a time, there was a guy named ORRA…………)