5.31 describe important uses of sodium hydroxide, including the manufacture of bleach, paper and soap; and of chlorine, including sterilising water supplies and in the manufacture of bleach and hydrochloric acid.

Uses of Sodium Hydroxide and Chlorine:

Sodium Hydroxide	Chlorine
Manufacture of Bleach	Sterilising water supplies
Manufacture of Paper	Manufacture of Bleach
Manufacture of Soap	Manufacture of hydrochloric acid
Manufacture of Detergents	Manufacture of PVC

5.30 write ionic half-equations for the reactions at the electrodes in the diaphragm cell

Positive electrode (anode):
Chloride ions lose electrons to form chlorine molecules

2Cl^- à Cl₂ + 2e^-

Negative electrode (cathode):

Water molecules gain electrons to form hydroxide ions and hydrogen molecules

2H₂O + 2e^- à 2OH^- + H₂

5.29 describe the manufacture of sodium hydroxide and chlorine by the electrolysis of concentrated sodium chloride solution (brine) in a diaphragm cell

Positive electrode (anode):
Chloride ions lose electrons to form chlorine molecules

2Cl^- à Cl₂ + 2e^-

Negative electrode (cathode):

Water molecules gain electrons to form hydroxide ions and hydrogen molecules

2H₂O + 2e^- à 2OH^- + H₂

Overall equation:

2NaCl + 2H­₂O à 2NaOH + H₂ + Cl₂

The diaphragm keeps the sodium hydroxide and chlorine apart to stop them forming bleach.

5.28 describe the use of sulfuric acid in the manufacture of detergents, fertilisers and paints

The 3 main uses of sulfuric acid are:

1. Manufacture of detergents
2. Manufacture of fertilisers
3. Manufacture of paints

5.27 describe the manufacture of sulfuric acid by the contact process

1. Sulfur Dioxide is made by burning sulfur in air
2. Sulfur dioxide is reacted with oxygen to form sulfur trioxide
3. Sulfur trioxide is absorbed into concentrated sulfuric acid to make oleum:

H₂SO₄(l) + SO₃(g) à H₂S₂O₇(l)

(Take note of the state symbols)

The oleum is then diluted to form a solution of sulfuric acid:

H₂S₂O₇(l) + H₂O(l) à 2H₂SO₄ (aq)

Process:

1. Air and Sulfur Dioxide are inputted 
2. The mixture of gases is cleaned, dried and heated to 400-500C and compressed to 2 atm. 
3. The mixture of gases is passed over the catalyst vanadium(V) oxide. Oxygen and sulfur combine to form sulfur dioxide and the yield is 98%.
4. Any unreacted gases are recycled. Sulfur trioxide is dissolved in concentrated sulfuric acid to form oleum. 
5. The oleum is diluted to form sulfuric acid.

5.26 recall the raw materials used in the manufacture of sulfuric acid

The raw materials of the contact process (manufacture of sulfuric acid):

• Sulfur dioxide
• Air

5.21 understand that condensation polymerisation produces a small molecule, such as water, as well as the polymer.

Condensation reactions takes two molecules and reacts them together to form a larger molecule and the elimination of a smaller molecule like water.
e.g.
Reacting a carboxylic acid and alcohol together forms an Ester with the elimination of a water molecule.