1.7 Oxidation, Reduction And Redox

Question 1

How can we remember oxidation and reduction?

Answer 1

OIL RIG

Question 2

What does OIL RIG stand for?

Answer 2

Oxidation is loss
Reduction is gain

(Referring to electrons)

Question 3

What is redox?

Answer 3

Something being oxidised and something being reduced

Question 4

How to form simple half equations?

Answer 4

Write the atom/ion and what it is being transferred to

Put the sufficient amount of electrons on either the left or right depending on whether it has been oxidised or reduced

Question 5

If something is being oxidised where in the half equation do the electrons go?

Answer 5

On the right side of the arrow

Electrons lost = oxidation

Question 6

If something is being reduced where in the half equation do the electrons go?

Answer 6

On the left side of the arrow

Electrons gained = reduction

(beyonce to the left to the left everybody know’s it reduction to the left)

Question 7

What is oxidation state?

Answer 7

Tells us how many electrons have been lost or gained

It is another method of interpreting redox reactions

Question 8

Where should you write the oxidation states?

Answer 8

Underneath the formula

Question 9

What are the rules for oxidation state?

Answer 9

Atoms of elements OS = 0
Simple ions the OS is the charge of the ion
Compounds the sum of the OS = 0
Covalent molecules are assumed to be ionic
Polyatomic ions the OS equals the overall charge of the ion

Question 10

How does electronegativity affect oxidation state?

Answer 10

The more electronegative a compound it is going to have a negative oxidation state

The less electronegative a compound it is going to have a positive oxidation state

Question 11

What are the fixed oxidation states of group 1 and 2 metals?

Answer 11

Group 1 = +1 OS

Group 2 = +2 OS

Question 12

What is the oxidation state of aluminium?

Answer 12

+3

Question 13

What is the oxidation state of oxygen? Exceptions?

Answer 13

-2

Except in peroxides and F2O

Question 14

What is the oxidation state of Fluorine?

Answer 14

-1

Question 15

What is the oxidation state of chlorine? Exceptions?

Answer 15

-1

Except in compounds with O or F

Question 16

What is the oxidation state of hydrogen? Exceptions?

Answer 16

+1

Except when bonded in a metal hydride = -1

Question 17

What does an increase in oxidation state from the reactant to the product side show?

Answer 17

Oxidation

Question 18

What does an decrease in oxidation state from the reactant to the product side show?

Answer 18

Reduction

It literally reduces

Question 19

How do you write more complex half equations?

Answer 19

Write down the formulae of the reactants and products and then balance the equation

Balance the oxygen by adding water
Balance the hydrogen by adding H+ ions
Balance the charges by adding electrons

Question 20

Why do you add water in more complex half equations?

Answer 20

Redox reactions are aqueous

Question 21

Why do you add hydrogen ions in more complex half equations?

Answer 21

Redox reactions are acidic

Question 22

Which side are the electrons normally added to in more complex half equations?

Answer 22

The side with the hydrogen ions

Question 23

What is an oxidising agent?

Answer 23

An electron acceptor

If it is reduced it is the oxidising agent

Question 24

What is a reducing agent?

Answer 24

An electron donor

If it has been oxidised it is the reducing agent

Question 25

How do you form overall redox reactions?

Answer 25

Combine the pair of half equations

You have to make sure the electrons in both equations are equal so you can cancel them out in the final equation

Therefore multiply one or both of all the equation so there are equal amounts in both the half equations

Question 26

How do you actually merge half equations?

Answer 26

Write all the reactants on one side and all the products on the other (after you multiplied accordingly)

Then cancel/simplify the long equation