d
The diagram shows a water heater. combustion products
hot water out
cold water in gas burning in air
air holes
e
If some of the air holes become blocked, a poisonous gas is produced. i State the name of this poisonous gas. ii Explain how this poisonous gas has been formed. The table below compares the amounts of carbon dioxide and sulfur dioxide formed when 1 kilogram of different fuels are burnt. Fuel
i ii iii iv
Mass of carbon dioxide produced / g
[2]
Mass of sulfur dioxide produced / g
oil
2900
5.0
gas
2500
0.1
coal
2500
11.0
Which fuel is least polluting? Which fuel, when burnt, contributes most to the formation of acid rain? State two harmful effects of acid rain. When acid rain falls on the ground, it can react with insoluble aluminium compounds in the soil. A solution of aluminium ions is formed. Describe what you would observe when aqueous sodium hydroxide is added to a solution containing aluminium ions.
[6]
CIE IGCSE, November 2003, paper 2, q.5
S
9
26
Minimising air pollution is essential for health and for the environment. a Natural gas is methane. i Write the equation for the complete combustion of methane. ii Explain why it is dangerous to use a gas fire in a poorly ventilated room. b Low-sulfur fuels are being introduced. Ordinary diesel contains 500 ppm of sulfur but low-sulfur diesel contains less than 50 ppm. Why is this an advantage to the environment?
IGCSE Chemistry
[2] [2] [2]