Topic 7- Redox

Question 1

What is oxidation

Answer 1

Oxidation is the loss of electrons

Question 2

What is Reduction

Answer 2

Reduction is the gain of electrons

Question 3

Examples of redox

Answer 3

Ca+1/2O2-> CaO

Ca-> Ca^2+2e^-2
1/2O2+2e^—> O^2-

Question 4

What is an oxidation state?

Answer 4

The number of electrons something needs to loose/ gain to be neutral

Question 5

What is the oxidation state of uncombined elements ?

Answer 5

Already neutral therefore oxidation state= 0

Question 6

What is the oxidation states of Ions:
1. K^+1
2. Al^3+
3. CL^-

Answer 6

Oxidation state is the same as the charge
ANSWERS:
1. +1 (Needs to gain an electron to be neutral)
2. +3
3.-1 (must lose an electron to become neutral)

Question 7

What are the rules for oxidation’s of oxygen?

Answer 7

Has a state of -2 unless in H202 or a compound with F!

Question 8

What does stock notation tell us?
Work out iron (II) oxide? (FeO)

Answer 8

Stock notation tells us the positive charge of the element!!
Therefore Fe has a +2 charge.

Question 9

Calculate the oxidation states of the following…
REMINDER!! Sum of oxidation states= overall charge
1. Oxidation state of C in CO2
2. Oxidation state of N in NH3

Answer 9

1. +4
2. N=-3

Question 10

How to write half equations??
(Rules)

Answer 10

1. Write what you know as an equation
2. Balance the atoms (Not the O or the H)
   3.Balance for O by adding H2O
3. Balance for H by adding H^+ ions.
4. Balance for charge by adding e^-

Question 11

What is a reducing agent?

Answer 11

Gets oxidised (gains electrons)
Then causes something else to be reduced therefore donates electrons (loses the electrons).

Question 12

What is an oxidising agent?

Answer 12

It becomes reduced (looses electrons)
Causes something to be oxidised (gains electrons)