Chemistry · May / June 2025 · Paper 61 · Question 4
0620
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Solid sodium hydrogencarbonate, NaHCO3, reacts with dilute hydrochloric acid and with dilute ethanoic acid. NaHCO3(s) + HC! (aq) NaC! (aq) + CO2(g) + H2O(l) NaHCO3(s) + CH3COOH(aq) CH3COONa(aq) + CO2(g) + H2O(l) These two reactions are endothermic. Plan an investigation to find which of the two reactions is the most endothermic. Your plan must include how you can use the results to find which reaction is the most endothermic. You are provided with solid sodium hydrogencarbonate, dilute hydrochloric acid, dilute ethanoic acid and common laboratory apparatus. [6]
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MP1 known / specified mass of sodium hydrogencarbonate
MP2 known / specified volume (and concentration) of hydrochloric or ethanoic acid
MP3 use of a named suitable container for the reaction and named suitable apparatus to measure volume of acid MP4 measure temperature of acid before mixing
MP5 add reagents together and mix / stir
MP6 measure temperature of mixture / acid after mixing / reaction
MP7 biggest temperature decrease is most endothermic
max 6
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