CHMY172 Chapter 17: Electrochemistry and Redox Reactions

Balancing redox reactions step 1

Identify what is being reduced, and what is being oxidized

Balancing redox reactions step 2

Balance everything that is NOT H or O

Balancing redox reactions step 3

Balance O by adding H₂O

Balancing redox reactions step 4

Balance H by adding H⁺ ions

Balancing redox reactions step 5

Balance e^- for each half reaction

Balancing redox reactions step 6

Balance e^- between half reactions

Balancing redox reactions step 7

Combine half reactions

Balancing redox reactions step 8

If in a basic environment, add in OH^- to cancel H⁺

Electrochemistry

How electrons move in reactions

Redox reactions

Oxidation-reduction reaction, one gains e^-, one loses e^-

Reduction

Gaining e^-

Oxidation

Losing e^-

OIL RIG

Oxidation is loss, reduction is gain

What steps in balancing redox reactions are not always required?

Steps 2 and 8

Salt bridge

Generate ions for regeneration of cations and anions

Cell notation

anode (s) | M anion (aq) || M cation (aq) | cathode (s)

+ charge

e- was lost

- charge

e- was gained

Cathode

Where reduction is occurring

Anode

Where oxidation is occurring

Galvanic cell

Redox reactions occur separately via a conductive wire and salt bridge

How can redox reactions occur when they are apart?

Using a wire for conductivity

E^o

Electric potential