Topic 7 - Electrochemistry

Question 1

Describe

Redox in terms of oxygen

Answer 1

Reduction is the loss of oxygen and oxidation is the addition of oxygen

Question 2

Redox in terms of electrons

Answer 2

Reduction is the gaining of electrons and oxidation is the loss of electrons

Question 3

Redox in terms of Hydrogen

Answer 3

Reduction is the addition of hydrogen and oxidation is the removal of hydrogen

Question 4

Redox in terms of oxidation number

Answer 4

Positive oxidation number means oxidation has taken place
Negative oxidation number means reduction has taken place

Question 5

Why do compounds have zero oxidation number?

Answer 5

The number electrons lost is equal to the number gained

Question 6

State rules for assigning oxidation numbers

Answer 6

The oxidation number of any uncombined element is zero
Sum of oxidation number ofan uncharged compounds is zero
The sum of oxidation number of an ion is equal to its charge
The more electronegative elements is assigned a negative charge
Group 1 elements are always +1
Group 2 elements are always +2
Fluorine is always –1
Hydrogen is +1, except in hydrides –1
Oxygen is –2, except in peroxides where it is –1

Question 7

Define

Dispropotronation

Answer 7

When one speeds is both oxidised and reduced in reaction simultaneously