Chemistry · Oct / Nov 2024 · Paper 62 · Question 4
0620
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Limes and lemons are citrus fruits which contain aqueous citric acid in their juice. Citric acid reacts with alkalis such as aqueous sodium hydroxide. Plan an investigation to nd which of lime juice and lemon juice contains the most concentrated aqueous citric acid. Assume that citric acid is the only acid present in the juices. Your plan must include: ● the method to use ● how the results are used to determine which juice contains the most concentrated aqueous citric acid. You are provided with lime juice, lemon juice, aqueous sodium hydroxide and common laboratory apparatus and chemicals. [6]
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any six from:
MP1 known / same / specified volume of juice
MP2 add a named acid-alkali indicator to the juice
MP3 suitable apparatus for titration (conical flask / beaker)
MP4 NaOH added from burette to juice
MP5 mix / swirl
MP6 indicator / juice changes colour
MP7 the juice that needs most NaOH is most concentrated
OR
MP1 known / same / specified volume of NaOH
MP2 add a named acid-alkali indicator to the NaOH
MP3 suitable apparatus for titration (conical flask / beaker)
MP4 juice added from burette to NaOH
MP5 mix / swirl
MP6 indicator / alkali changes colour
MP7 the juice with the smallest volume is most concentrated
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