Changing the temperature
2 marks · EasyA reversible reaction has for the forward reaction. Explain how you can tell from the value whether the forward reaction is exothermic or endothermic.
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The ΔH value is positive, which means energy is absorbed by the forward reaction, so the forward reaction is endothermic.
Also accept: A positive ΔH shows the forward reaction is endothermic
Common mistakes: Says exothermic for positive ΔH
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Marking points
M1 · 1 mark · States that a positive ΔH means energy is absorbed by the forward reaction.
A1 · 1 mark · Concludes that forward reaction is endothermic.
Worked solution
ΔH is positive, meaning the forward reaction absorbs heat from the surroundings. This defines an endothermic reaction.