Unit 12: Sulfur

Question 1

What are some of the sources of sulfur?

Answer 1

1. It can be extracted from metal ores like copper pyrites and zinc sulfide.
2. From compounds found in oil.

Question 2

What are some of the uses of sulfur?

Answer 2

1. To make sulfuric acid.
2. To vulcanise rubber, making it tougher.
3. In gunpowder.

Question 3

What are some of the uses of sulfur dioxide?

Answer 3

1. As a bleach in the manufacture of wood pulp.

2. As a food preservative (by killing bacteria).

Question 4

How is sulfuric acid manufactured by the contact process?

Answer 4

1. Sulfur is burned in air, S + O2 –> SO2.
2. The sulfur dioxide is reacted further with oxygen with the catalyst vanadium pentoxide, 2SO2 + O2 –> 2SO3.
3. The sulfur trioxide reacts with concentrated H2SO4 to form H2S2O7, SO3 + H2SO4 –> H2S2O7.
4. The H2S2O7 reacts with water, H2S2O7 + H2O –> 2H2SO4.

Question 5

What are the essential conditions required in the contact process?

Answer 5

1. Vanadium pentoxide is required as a catalyst.

2. A temperature of around 450C.

Question 6

What are the properties of dilute sulfuric acid?

Answer 6

1. It is a relatively good conductor of electricity (because there are many ions due to water ionising the sulfuric acid molecules).
2. In an exam you can list acid + base, acid + metal and acid + carbonate where dilute sulfuric acid is the acid.

Question 7

What are the properties of concentrated sulfuric acid?

Answer 7

1. Poor conductor or electricity (because there are few ions, there is mainly just molecules).
2. Viscous.
3. Oily.
4. Dense.
5. Colourless.
6. Can be used as a dehyrdating agent (removes the water of crystallisation and decomposes sucrose to carbon and water).

Question 8

What are some of the uses of sulfuric acid?

Answer 8

1. In the production of fertilisers like ammonium sulfate.
2. In paints, pigments and dyes.
3. To remove oxides from iron and steel before galvanising or electroplating.