Topic 3 Redox

Question 1

what is a redox reaction

Answer 1

reaction which involves both oxidation & reduction

Question 2

what is oxidation

Answer 2

loss of electrons

Question 3

what is reduction

Answer 3

gain of electrons

Question 4

what is an oxidising agent

Answer 4

species which oxides another by removing one or more electron but is reduced itself

Question 5

what is a reducing agent

Answer 5

species which reduces another species by adding one or more electron thus being oxidised itself

Question 6

what is oxidation number

Answer 6

is the charge that an ion has or the charge that it would have if the species was fully ionic

Question 7

what does an increase of ox.number mean

Answer 7

oxidation

Question 8

what does a decrease of ox.number mean

Answer 8

reduction

Question 9

what are the 9 rules of determining oxidation number

Answer 9

1. The oxidation number of an uncombined element is zero
2. The oxidation number is the same as charge on ion
3. The sum of the oxidation numbers of all the elements in a neutral compound is zero

4 . The oxidation num of fluorine is always - 1

5. The ox. num of hydrogen is + 1 except in hydrides where it’s - 1 e.g. NAH
6. The ox num of chlorine is - 1 except in a compound with F and O it would have a positive value
7. The ox num of oxygen is - 2 except in peroxides where it’s KE - 1 and + 2 in OF 2
8. The more electronegative element in a substance is given a negative ox . num
9. The sum of ox num of each element in an ion is equal to the charge on the ion

Question 10

what is disproportion

Answer 10

is the simultaneous oxidation & reduction of an element in a single reaction

Question 11

steps to forming half equations

Answer 11

1. write down species before + after reaction
2. Balance any atoms/elements apart from oxygen + hydrogen
3. Balance oxygens with H2O
4. Balance hydrogens with H+ ions
5. Balance charges with e-