Topic (Experiment): Determining Ascorbic Acid in Vitamin C tablets . 1.) A stude

ID: 492123 • Letter: T

Question

Topic (Experiment): Determining Ascorbic Acid in Vitamin C tablets.

1.) A student collected the following data in the lab:

- mass of flask: 52.87 g

- mass of flask & sample: 53.42 g

- concentration of NaOH solution: 0.101 M

- initial buret reading: 0.50 mL

- final buret reading: 23.78 mL

(a) what is the mass, in grams, of the sample?

(b) what volume, in litters, of NaOH fo solution was used in the titration?

(c) how many moles of NaOH solution were used in the titration?

(d) how many moles of ascorbic acid were neutralized?

(e) how many grams of ascorbic acid is this?

(f) what is the mass % ascorbic acid in the sample?

(please include the calculation)

Given that :

Mass of the flask = 52.87g

Mass of flask and sample = 53.42g

Concentration of NaOH solution = 0.101M

Initial burette reading = 0.50 mL

Final burette reading = 23.78 mL

(a) Mass of the sample (in grams) = Mass of flask and sample - Mass of the flask

= 53.42g - 52.87g = 0.55g

(b) Volume of NaOH solution used in the titration = Final burette reading - Initial burette reading

= 23.78 mL - 0.50 mL = 23.28 mL

Therefore, the volume of sodium hydroxide solution in litres used in the titration is:

23.28 mL/1000 mL = 0.02328L

(d) Number of mole of NaOH reacted with ascorbic acid = 2.33 x 10-3 moles

Number of moles of ascorbic acid neutralised is therefore, 2.33 x 10-3 moles

(e) Number of grams of ascorbic in the above case is:

176 (molar mass) x 2.33 x 10-3 moles = 0.41g

(f) Mass % of ascorbic acid in the sample is:

Mass of the sample / Molar mass of sample x 100 = 0.313

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