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Forward reaction energy profile
One stage in the industrial production of sulfuric acid is the reaction of sulfur dioxide with oxygen to produce sulfur trioxide. This reversible reaction reaches dynamic equilibrium. Figure 7 shows the percentage yield of sulfur trioxide in this reaction at different temperatures.
Which statement about the forward reaction is correct? Use Figure 7. Tick one box.
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Marking points
- 1 Selects ‘The yield is smaller at higher temperatures because the reaction is exothermic.’
Why this answer loses marks
Higher temperature always gives more product because particles react faster.
That confuses rate with equilibrium yield; the graph trend must be linked to the heat direction of the forward reaction.