XSIQ
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Chemistry - Volumetric analysis - activity 14

Volumetric analysis - activity 14

The citric acid C6H8O7 content of orange juice can be determined by
titration with aqueous sodium hydroxide. A 26.3 g sample of orange juice
was diluted to 250.0 mL with water using a volumetric flask. A 25.0 mL
aliquot of the diluted juice was titrated with 0.0114 M NaOH(aq), using
phenolphthalein indicator. A titre of 22.37 mL was obtained.

The reaction occurring can be represented by the equation:

(a) Write an ionic equation for the reaction occurring the titration.

(b) How many moles of NaOH were used in the titration.

(c) How many of moles of citric acid were present in 25.0 mL of diluted
orange juice.

(d) How many moles of citric acid were present in the 250.0 mL volumetric
flask of diluted juice.

(e) How many moles of citric acid were present in the original sample of
orange juice.

(f) Determine the mass of citric acid in the original sample of orange
juice.

(g) Determine the percentage, by mass, of citric acid in the orange juice.

(h) If the burette used in the titration was rinsed with water before the
sodium hydroxide solution was added, would the calculated amount of citric
acid in the orange juice be the same as, greater than or less than the true
value?

Answer

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