The combustion of elements in oxygen
2 marks · NormalSuggest one reason why some elements burn more brightly in pure oxygen than in air. Name an element that burns brightly in oxygen.
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Also accept: There is a higher concentration of oxygen in pure oxygen so elements burn more vigorously.; Magnesium
Common mistakes: Giving 'hydrogen' as the element; Stating 'air has oxygen' without making a comparison
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Marking points
B1 · 1 mark · Suggests oxygen concentration is higher, causing a more energetic reaction.
B2 · 1 mark · Names a suitable element (e.g. magnesium, sodium, phosphorus).
Worked solution
Pure oxygen contains a higher percentage of oxygen than air, so elements burn more energetically or brightly.
Example: Magnesium burns with a bright white light in oxygen.