High School
SAT
ACT
University
MCAT
LSAT
DAT
Wize University Chemistry Textbook > Electrochemistry

Redox Reactions

Oxidation States Previous Section
Balancing Redox ReactionsNext Section
Popular Courses
Find My Course
0:00 / 0:00

Redox Reactions

OIL RIG! Oxidation Is Loss of electrons, Reduction Is Gain of electrons
OR
LEO GER! Loss of Electrons is Oxidation, Gain of Electrons is Reduction

OXIDATION (lose e-) REDUCTION (gain e−)

_____________

Reducing agent reduces others and is itself Oxidizing agent oxidizes others and is itself
oxidized. reduced.

Oxidation number increases. Oxidation number is reduced.


PAGE BREAK


Keep in mind that in organic chemistry the definitions of oxidation and reduction are different:
  • For reduction, we would look for more bonds to H and less bonds to O
  • For oxidation, we would look for less bonds to H and more bonds to O!


PAGE BREAK

How can you recognize if a redox reaction is occuring?

1. Can check oxidation #s of each element to see if they change from reactants to products (most important for now!)

2. Familiarize yourself with common oxidizing and reducing agents (you'll learn more about this in orgo!)
  • Oxidizing agents: O2, halogens, HNO3, Cr2O72-, MnO4-
  • Reducing agents: H2, metals, C



Practice: Oxidation vs Reduction

Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is being oxidized?

Practice: Oxidizing vs Reducing Agent

Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is the reducing agent?

Practice: Oxidizing vs Reducing Agents

What is the reducing agent in the following chemical reaction?

NO + Au+ → NO3- + Au
Extra Practice
Electrochemistry: Redox
What is the reducing agent in the following unbalanced chemical reaction?
NO + Au+ → NO3- + Au
Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is the reducing agent?
Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is the oxidizing agent?
Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is being reduced?
Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Which species is being oxidized?
Consider the following balanced redox equation:
16H(aq)++2MnO4(aq)−+10Cl(aq)−→2Mn(aq)2++5Cl2(g)+8H2O(l)16H^+_{(aq)}+2MnO^-_{4(aq)}+10Cl^-_{(aq)} \to 2Mn^{2+}_{(aq)}+5Cl_{2(g)}+8H_2O_{(l)}
Would you use an oxidizing or reducing agent for the following reaction to occur?
SO42- --> S2-
What product forms at each electrode in the aqueous electrolysis of the following salts? Ignore overpotential effects.
LiF
SnSO4
A concentration cell consists of two H2/H+ half-cells. Half-cell A has H2 at 0.90 atm bubbling into 0.10 M HCl. Half-cell B has H2 atm bubbling into 2.0 M HCl. Which half-cell houses the anode? What is the voltage of this cell?
Redox
C2O42−(aq) + MnO4−(aq) → CO32−(aq) + MnO2(s)
Which one is the reducing agent in this equation?
Similar to Practice Exam 1 Fall 2018 (CHM 2045 UF)
What is the oxidizing agent in the following unbalanced chemical reaction?
NO + Au+ → NO3- + Au