Chapter 12

Question 1

Name some sources of sulfur

Answer 1

In mines, volcanic emissions, hot springs, hydrothermal vents and as a by product of the oil-refining industry.

Question 2

State the use of sulfur in the manufacture of

sulfuric acid

Answer 2

Sulfur burns in air to form sulfur dioxide which is used to form sulfur trioxide and so on to produce sulphuric acid.

Question 3

State the uses of sulfur dioxide

Answer 3

As a bleach in the manufacture of wood pulp for paper and as a food preservative (by killing bacteria)

Question 4

Describe the manufacture of sulfuric acid by the Contact process, including essential conditions and reactions

Answer 4

1. S (s) + O2 (g) → SO2 (g)
   Sulfur burns in air to form sulfur dioxide
2. 2SO2 (g) + O2 (g) ⇌ 2SO3 (g)
   Sulfur dioxide and some leftover oxygen react with the use of the catalyst Vanadium (V) oxide (V2O5) to form sulfur trioxide.
3. SO3 (g) + H2SO4 (l) → H2S2O7 (l)
   Sulfuric acid is added to sulfur trioxide to form oleum
   [it must be sprayed on because otherwise gases might form and escape and cause acid rain; therefore acid scrubbers must be used as sulfur dioxide is acidic]
4. H2S2O7 (l) + H2O → 2H2SO4 (l)
   Water is added to oleum to form sulfuric acid.
   The essential conditions needed for this to occur is a vanadium oxide catalyst, 450˚C and a pressure of 2 atm.

Question 5

Describe the properties and uses of dilute and concentrated sulfuric acid

Answer 5

They both have a low pH, react with bases, highly conductive, forms sulphates. Diluted, it reacts with metals to form a salt and hydrogen gas, with carbonates to form carbon dioxide, salt and water and with metal oxides to form a salt and water. However for concentrated, they are highly corrosive and act like a dehydrating agent.

Question 6

State the uses of sulfur

Answer 6

• Used to produce concrete, pesticides and medicines.
• Used to produce Sulfur dioxide, used as bleach and as
  a preservative.
• Manufacturing of sulfuric acid.