Oxidation and Reduction

Oxidation

Losing Electrons

Reduction

Gaining Electrons

Reducing Agent

Losing Electrons and is oxidized

Oxidizing Agent

Gains electron is reduced

Common Oxidizing Agents

O2, O3, H2SO4, Halogens

Common reducing agents

H2, Fe, Zn, Alakali Metals

Oxidation Number

total number of electrons that gain or loses when a bond is formed

Oxidation Number State Rule 1

Atoms in their elemental state are assigned number 0

Oxidation Number Rule 2

OXidations numbers for atoms in monatomic ions are equal to charge

Na+ = 1, Mg 2+ = 2 or Se 2- = -2

Oxidation Rule 3

Flurorine is always assigned -1

oxygen is in peroxide (H2O2) oxidation of oxygen is -1

Oxygen bonded to flourine than oxygen is +1

Hydrogen is part of a metal hydride MgH2 Hydrigen has -1

Oxidation Rule 4

Alkali mEtals = 1

Alkaline metals = 2

Direction of Charge meabs in terms of electrons

going up means losing electrons

goign down means gaining electrons

balance redox reactions in acids

1. write out half reactions

2. balance all atoms in eqatuion other than O and H

3. Balance the oxygen atoms by adding the same number of H2O molecules to the oppo side

4. balance the H atoms by adding H+ ions to the oppo side

5. determine if the charges are the same if not add e- to the more pos side

6. number of e in both reactions must be the same

   1. half reactions are added togehter and electrons should cancel to bal out

Balance Redox Reaction in Basic Conditions

1. write out half reactions

2. balance all atoms in eqatuion other than O and H

3. Balance the oxygen atoms by adding the same number of H2O molecules to the oppo side

4. balance the H atoms by adding H+ ions instead to the oppo side

5. FOR BASIC CONDTIONS add the same amount of OH- as H+ ions to the both side

6. The H+ and OH combine into H2O

   1. AFTER Continue as normal

Electrochemical Cells

Convery Chemical Energy to Electrical energy using redox reactions

AN OX

anode = site of oxidation negative

Red Cat

Site of reduction = Cathode postiive

ELECTRONS always flow from what

electrons always flow from anode to the cathode

Galvanic or Voltaic Cell

Sponatenous

Electrolytic cell

non sponatenous