TOPIC 3: Redox 1

Question 1

Oxidising agent

Answer 1

Gains electrons, reduced.

Question 2

OIL RIG

Answer 2

Oxidation is loss, reduction is gain.

Question 3

Reducing agent

Answer 3

Loses electrons, oxidised

Question 4

Uncombined elements - oxidation numbers

Answer 4

Always 0

Question 5

Ions - oxidation numbers

Answer 5

Same as charge on ion

Question 6

Groups 1, 2, Aliminium, Fluorine - oxidation numbers

Answer 6

Always 1, always 2, always 3, always -1

Question 7

Hydrogen, Oxygen, Chlorine (exceptions) - oxidation numbers

Answer 7

1 (except -1 in hydrides eg:NaH), -2 (except -1 in peroxides H2O2 and +2 in OF2)
-1 (except positive in F or O compound eg: 3 in ClF3)

Question 8

Disproportionation reaction

Answer 8

Same species gets simultaneously oxidised and reduced

Question 9

Balancing Half Equations steps (6) if alkaline conditions (+3)

Answer 9

• Species before and after reaction.
• Balance atoms
• Balance oxygens (H2O)
• Balance hydrogens (H+ ions)
• Balance charges with e-
• Combine 2 to make full ionic
  (no e-) equation by balancing e-

If alkaline conditions, as well:
- add same n of OH- as H+ on both sides
- combine to make water and cancel waters out
- equate