1.7- redox

Question 1

Describe what happens when a reaction mixture is refluxed and why it is necessary for complete oxidation of ethanol to ethanoic acid (3)

Answer 1

-a mixture of liquids is heated to a BP for a prolonged time
-vapour is formed which escapes the liquid mixture, then changed back to liquid and returned to the liquid mixture
-any ethanol/ethanal that initially evaporates can then be oxidised

Question 2

what are the 4 exceptions of elements when combined

Answer 2

1. O= -2 (except when combined with F, it is +1/+2 and in peroxide 2. H2O2, where it is -1)
2. H= +1 (except in metal hydrides eg. LiH, where it is -1)
3. F= -1 ALWAYS (eg. in F2O, it is -1 and O is +2)
4. Cl= -1 (except when combined with F or O eg. ClF, where it is +1)

a lower number rule takes precedence over a higher number rule

Question 3

what is oxidation and an oxidising agent

Answer 3

oxidation= loss of electrons
oxidising agent= electron acceptor (has to be reduced)

Question 4

what is reduction and a reducing agent

Answer 4

reduction= gain of electrons
reducing agent= electron donor (has to be oxidised)

Question 5

4 steps to balancing equations

Answer 5

1. balance species
2. balance oxygens using H2O
3. balance hydrogens using H+
4. balance charge using e- (take into account the numbers in front of molecules eg. 2H+)