Oxidation and Reduction

Question 1

Oxidation

Answer 1

Increase in oxidation state (charge)

Loses electrons

Metals go through oxidation usually

Question 2

Reduction

Answer 2

Decrease in oxidation state
Gain of electrons

Nonmetals go through reduction usually

Question 3

Oxidation agent

Answer 3

The substance that is being reduced (gains electrons) and causes the other substance to oxidize (lose electrons)

Non-metals are oxidation agents

Question 4

Reducing agent

Answer 4

The substance that is being oxidized in the reaction and causes the other substance to be reduced (gain electrons)

Metals are reducing agents

Question 5

How are oxidation half-reactions identified

Answer 5

When the electrons are on the right side it is an oxidation half-reaction

Question 5

How are reduction half-reactions identified

Answer 5

When electrons are on the left side it is an reduced half-reaction

Question 6

Oxidation-Reduction Reaction

Answer 6

An electron-transfer reaction

Question 7

Disproportionation reaction
3 BrF → BrF3 + Br2
bromine is being both oxidized and reduced

Answer 7

A reaction where the same species can undergo both oxidation and reduction

3 BrF → BrF3 + Br2
bromine is being both oxidized and reduced

Question 8

Rules for assigning oxidation numbers

Answer 8

1. the sum of oxidation numbers for each atom or ion in a compound
   must equal the overall charge of the compound
   * atoms in elemental forms have oxidation numbers of zero: H2(g), O3(g), Na(s),
   P4(s), etc.
   * monatomic ions have oxidation numbers equal to their charge: Cu+ ox # = +1, S2-
   ox # = –2, etc.
2. Assign oxidation numbers of +1 to Group 1A metal cations and +2 to Group 2A metal cations
3. Assign fluorine an oxidation number of –1
4. Assign hydrogen an oxidation number of +1 unless otherwise dictated by
   previous rules
   * NaH, CaH2
5. Assign oxygen an oxidation number of –2 unless otherwise dictated by
   previous rules
   * H2O2, OF2, NaO2
6. Assign Group 7A nonmetals (Cl, Br, I) oxidation numbers of –1 unless otherwise dictated by previous rules
7. Assign Group 6A nonmetals (S, Se, Te) oxidation numbers of –2 unless otherwise dictated by previous rules
8. Assign Group 5A nonmetals (P, As, Sb) oxidation numbers of –3 unless otherwise dictated by previous rules

Question 9

What type of reactions are redox

Answer 9

Single replacement reactions and combustion reactions

Question 10

What type of reactions are not redox

Answer 10

Precipitation reactions
Acid-base neutralization reactions
Double replacement reactions

Question 11

What is the minimum and maximum oxidation numbers for nitrogen

Answer 11

minimum ox # = Group # – 8 (5–8 = –3); maximum ox # = Group # (+5)

Question 12

What is the minimum and maximum oxidation numbers for sulfur?

Answer 12

minimum ox # = Group # – 8 (6–8 = –2); maximum ox # = Group # (+6)

Question 13

What is the minimum and maximum oxidation numbers for chlorine?

Answer 13

minimum ox # = Group # – 8 (7–8 = –1); maximum ox # = Group # (+7)

Question 14

When a species has a maximum oxidation # what can only happen?

Answer 14

it can only be reduced (i.e., gain
electrons) and act as an oxidizing agent
* NO3–, SO42–, ClO4–

Question 15

When a species has its minimum oxidation # what can happen?

Answer 15

it can only be oxidized (i.e., lose
electrons) and act as a reducing agent

Question 16

When a species has its intermediate oxidation #, what can only happen?