Redox Reactions and Oxidation Numbers, Slides of Pharmacy

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CHE 156 Course Outline

Atoms and Molecules

Acids, Bases and Salts

Thermochemistry

Oxidation and ReductionReactions/

Electrochemistry (Dr. Onyinyechi V. Uhuo)

Rates of Reactions

Kinetic Theory of Gases

REDOX Reaction Outline

• Definition of Terms
• Identifying Redox Reactions
• Oxidizing/Reducing Agents
• Calculation of Oxidation numbers
• Balancing Redox Equations Background Knowledge
• Atomic numbers
• Loss or gain of electron
• Sign convention due to loss and gain of electrons

1. Definition in terms of oxygen

Oxidation is the addition of oxygen to a substance

while Reduction is the removal of oxygen from a

substance

Example 1: Extraction/production of metals by reduction of their ores (which exist as metal oxides in most cases) to the metal. E.g production of iron from iron ore (hemitite)

Oxidizing agent is the substance that is reduced

Reducing agent is the substance that is oxidized

An oxidizing agent in one reaction can act as the reducing agent in another reaction

reduction oxidation (reduction)

2. CO → CO 2 (addition of oxygen) (O.A) (R.A)

Zn (s)

• CuSO 4(aq) → ZnSO 4(aq)
• Cu (s) Example 3: oxidation reduction (Oxidation) CuSO 4 is reduced to Cu (CuSO 4 is the O.A) (R.A) (O.A)

2. Definition in terms of hydrogen

• Oxidation is the removal of hydrogen from a compound.
• Reduction is the addition of hydrogen to a compound

Hydrocarbon CH + O 2(g) → CO 2(g)

• H 2 O (l) Example 6: Combustion of Hydrocarbon. oxidation reduction Oxidation) O 2 is reduced to H 2

O (O

2 is the O.A) (R.A) (O.A)

C 6 H 12 O 6

• 6O 2(g) → 6CO 2(g)
• 6H 2 O (l) Example 7: Cellular Respiration (oxidation of glucose). oxidation reduction O 2 is reduced to H 2

O (O

2 is the O.A) (R.A) (O.A) https://micro.magnet.fsu.edu/cells/ mitochondria/mitochondria.html

3). Definition in terms of oxidation number (electron )

3). Definition in terms of oxidation number (electron )

• Oxidation is the loss of electron
• Oxidation is the increase in the oxidation number
• Reduction is the gain of electron
• Reduction is the decrease in the oxidation number Oxidation number increases Oxidation number decreases (^14)

Addition of metallic zinc to an aqueous CuSO 4 , which is blue, to give a colourless aqueous solution of ZnSO 4 and a red-brownish deposit of Cu metal. Zn (s) CuSO 4(aq) ZnSO 4(aq) Cu (s) This reaction can be divided into two halves, called half-reactions, the oxidation reaction and the reduction reaction. Zn (s)

• CuSO 4(aq) → ZnSO 4(aq)
• Cu (s) 16

Zn (s)

• CuSO 4(aq) → ZnSO 4(aq)
• Cu (s) Example 8: oxidation reduction (R.A) (O.A)

2Na (aq)

• H 2(s) → 2NaH (s) Oxidation (R.A) Na is oxidized to NaH (NaH is the R.A) Example 9: reduction (O.A) 3). Definition in terms of oxidation number (electron )