1. Iron is extracted from its ore, hematite, in a blast furnace.

Substances added to the furnace are:

• Iron ore, hematite, containing impurities such as silica, SiO₂

• Air

• Coke, C

• Limestone, CaCO₃

Substances formed in the blast furnace are:

• Molten iron

• Molten slag

• Waste gases such as carbon dioxide

State the two functions of the coke used in the blast furnace.