3 - Redox I

Question 1

What is an oxidation number?

Answer 1

A representation of how oxidised/reduced an element becomes in a reaction, telling you how many electrons have been lost/gained.

Question 2

What is oxidation?

Answer 2

LOSS of electrons - oxidation number INCREASES

Question 3

What is reduction?

Answer 3

GAIN of electrons - oxidation number DECREASES

Question 4

What are the rules of oxidation numbers?

Answer 4

• An unconvinced element’s oxidation number is always 0.
• In a neutral compound, the sum of all the oxidation numbers is 0.
• Simple monoatomic ions have oxidation numbers that are the same as their charges.
• In compounds, the oxidation number is the same as the overall charge of the ion.
• For G1/2, the oxidation number is the same as the group number.

Question 5

What is hydrogen’s oxidation number and are there any exceptions to this?

Answer 5

+1

-1 in metal hydrides (because the oxidation number = the ion charge)

Question 6

What is the oxidation number of Fluorine and are there any exceptions to this?

Answer 6

-1

No exceptions

Question 7

What is the oxidation number of oxygen and are there any exceptions to this?

Answer 7

-2
-1 in peroxides because neutral compounds = 0
Positive with F as F is more electronegative than O

Question 8

What are the oxidation numbers of Cl, Br and I - are there any exceptions to this?

Answer 8

All -1
Cl: positive with O or F
Br: positive with O, F or Cl
I: positive with O, F, Cl or Br

Question 9

What does the Roman numeral in Copper (II) Sulphate indicate?

Answer 9

Copper’s oxidation number is +2.

Question 10

What is are oxidising and reducing agents?

Answer 10

• Oxidising: GAINS electrons, becoming reduced as a result (decreasing oxidation number) - NON-METALS
• Reducing: LOSES electrons, becoming oxidised as a result (increasing oxidation number) - METALS

Question 11

What is a redox reaction?

Answer 11

When oxidation and reductio occur simultaneously within a reaction.

Question 12

What is a disproportionation reaction?

Answer 12

A redox reaction where a single species is simultaneously oxidised and reduced.

Question 13

When creating full equations from half equations, what steps must you take?

Answer 13

1. ) Balance everything EXCEPT for O and H
2. ) Balance for O by adding H2O
3. ) Balance for H by adding H+
4. ) Balance charge using e-