2.1.5 Redox

Question 1

What’s oxidation a gain of (1) and a loss of (2)

Answer 1

Gain of oxygen
Loss of hydrogen
Loss of electrons

Question 2

What’s reduction a loss of (1) and a gain of (2)

Answer 2

Loss of oxygen
Gain of hydrogen
Gain of electrons

Question 3

What happens to magnesium as it burns in oxygen

What happens to the oxygen

Answer 3

Gets oxidised (gains oxygen & loses 2e-)

Oxygen gets reduced (gains 2e-)

Question 4

Why are they called redox reactions

Answer 4

As oxidation can’t occur without a reduction also occurring

Question 5

How do we show electrons gained/lost in redox

Answer 5

By splitting the full equation into 2 half equations

1 shoes oxidation
1 shows reduction

Question 6

What electrons are always on the left of the arrow in half equations

Answer 6

The gaining electron

Question 7

What reactions are redox in disguise

Answer 7

Displacement reactions

Question 8

What does an ionic equation show

Answer 8

The ions that take part

Question 9

4 halogens and their halides

Answer 9

Fluorine, F2 - Fluoride, F-
Chlorine, Cl2 - Chloride, Cl-
Bromine, Br2 - Bromide, Br-
Iodine , I2 - Iodide, I-

Question 10

What do group 7 elements switch between in redox

Answer 10

The halogen form and halide form

Question 11

How can we decide which species is being oxidised or reduced if the reactions doesn’t involve oxygen/hydrogen

Answer 11

By observing the electron transfer

Question 12

What are the 6 oxidation state rules

Answer 12

1. Elements always zero
2. Group 1,2,3 metals always charge an ion
3. Hydrogen is +1 except when with group 1,2,3 metals (is -1)
4. Oxygen is -2 except when peroxide (is -1)
5. In neutral compounds the OS must add up to 0
6. In more complex ions the oxidation state must add up to the charge on the ion

Question 13

What must OS state add up to in neutral compounds

Answer 13

0

Question 14

What must the OS add up to in more complex ions

Answer 14

The charge of the ion

Question 15

What has happened to the element if the OS state goes up

Answer 15

Oxidised

Question 16

If the OS goes down what happens to the element

Answer 16

It’s reduced

Question 17

What’s a reducing agent

Answer 17

Gives away electrons (electron donor)

Question 18

What’s an oxidising agent

Answer 18

Removes electrons (electron acceptor)

Question 19

What must an oxidising agent become itself

Answer 19

Reduced

Question 20

What must a reducing agent become itself

Answer 20

Oxidised

Question 21

How can a half equation be made

Answer 21

Splitting a full equation

Question 22

5 rules for half equations

Answer 22

1. Balance atoms undergoing redox
2. Balance oxygens by adding water
3. Balance hydrogens by adding H+
4. Balance charges by adding/subtracting electrons
5. Add state symbols

Question 23

When half equation reactions are carried out, what conditions are used and why

Answer 23

Under acidic aqueous conditions

Acid provides H+ ions
Aqueous medium provides water

Question 24

What makes up a full redox equation

Answer 24

A reduction half-equations being added with an oxidation half-equation

Question 25

What must cancel out when making a full redox equation

Answer 25

The electrons when the 2 are added together

Question 26

What should you do if number of electrons doesn’t match

Answer 26

Multiply to find a common number

Question 27

What’s oxidised and reduced in a MASH reaction

Answer 27

Metal - oxidised

Hydrogen - reduced

Question 28

What do we use to tell us oxidation number

Answer 28

Roman numerals

Question 29

What do compounds ending -ate contain

Answer 29

Oxygen and another element