Pollutants from Burning Fuels · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

What else comes out of the flame

Science · Matter & Materials · ages 15-16
Name ______________________   Date ____________

  1. Why is a faulty gas heater dangerous even when the flame looks fine?

    • It uses up all the nitrogen in the room
    • It turns the gas supply acidic
    • It may give off colourless poisonous carbon monoxide

  2. Which pair comes from complete combustion of a hydrocarbon?

    • Carbon monoxide and soot
    • Carbon dioxide and water
    • Sulfur dioxide and nitrogen oxides

  3. Sulfur dioxide from fuels dissolves into rain and falls as acid rain.

    Circle one:   True   False

  4. How does sulfur in fuel end up as acid rain?

    • It burns to SO2, which dissolves into rain
    • It sinks into the ground at the pump
    • It turns straight into soot in the tank

  5. Nitrogen is normally unreactive. Why do engines still make nitrogen oxides?

    • Petrol already holds nitrogen oxides inside
    • Engine heat fuses nitrogen and oxygen
    • Exhaust pipes cool nitrogen too fast

  6. A town fits scrubbers to its power plant. What is the trade-off?

    • Cleaner air with no cost at all
    • More electricity generated for free
    • Less SO2, but money and energy to run them

  7. Which pollutant comes from the air itself rather than the fuel?

    • Nitrogen oxides
    • Sulfur dioxide
    • Soot

  8. A room has soot marks and headaches, though the flame looks fine. What is the likely cause?

    • Complete combustion with extra oxygen
    • Incomplete combustion giving CO and soot
    • Nitrogen oxides from cold air
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Answer key

For grown-ups. Fold this page away before handing over the rest.

What else comes out of the flame W1-mt_DDiyDBy6YW-s1

  1. It may give off colourless poisonous carbon monoxide · Incomplete combustion makes CO, which you cannot see or smell.
  2. Carbon dioxide and water · Plenty of oxygen burns every carbon fully to CO2 and every hydrogen to water.
  3. True · Burnt sulfur becomes SO2, which dissolves into rain and acidifies it.
  4. It burns to SO2, which dissolves into rain · Burnt sulfur leaves as a gas, then rains down acidic.
  5. Engine heat fuses nitrogen and oxygen · Extreme engine heat forces the two air gases to combine.
  6. Less SO2, but money and energy to run them · Scrubbers strip sulfur but need building, power and upkeep.
  7. Nitrogen oxides · Nitrogen oxides fuse nitrogen and oxygen that the engine breathed in.
  8. Incomplete combustion giving CO and soot · Soot plus sickness points to a starved flame making CO.
Worksheet · LightMySky