Topic 3

Question 1

Oxidation

Answer 1

Loss of electrons
Increase in oxidation number

Question 2

Reduction

Answer 2

Gain of electrons
Decrease in oxidation number

Question 3

Reducing agents

Answer 3

Lose electrons and are oxidised themselves

Question 4

Oxidising agents

Answer 4

Gain electrons and are reduced themselves

Question 5

Oxidation numbers rules: Uncombined elements

Answer 5

Always 0

Question 6

Oxidation number rules: Ions

Answer 6

Number is same as charge on ion

Question 7

Oxidation number rules: Aluminium

Answer 7

Always +3

Question 8

Oxidation number rules: Hydrogen

Answer 8

Always +1 (except in hydrides -when hydrogen is bonded to a metal- where it is -1)

Question 9

Chlorine

Answer 9

-1 (except when in a compound with F or O - would have positive value)

Question 10

Fluorine

Answer 10

Always -1

Question 11

Oxygen

Answer 11

-2 (except it’s -1 in peroxides -H2O2- and +2 in OF2)

Question 12

Disproportionation reaction

Answer 12

A REDOX reaction where a single species is simultaneously being reduced and oxidised

Question 13

Balancing half equations

Answer 13

1) Balance any atoms apart from oxygen or hydrogen.
2) Balance oxygens with H20.
3) Balance hydrogens with H+ ions.
4) Balance charges with electrons.