Essay about Quantitative Analysis of Vitamin C Contained in Ribena

639 WordsMar 31, 20113 Pages
Title: Quantitative analysis of vitamin C contained in ribena Aim: to determine the amount of Vitamin C in a sample of ribena Materials: * Vitamin C (ascorbic acid, C6H8O6) * 4% potassium iodide (KI) * 1M acetic acid (CH3COOH) * N-bromosuccinimide (NBS, C4H4BrNO2) Apparatus: * Conical flask * 100 ml volumetric flask * Weighing bottle * Analytical weight balance * Spatula * Funnel Results: Item: | Mass in grams | Mass of weighing bottle with ascorbic acid | 23.4224 | Mass of empty weighing bottle | 23.2883 | Mass of ascorbic acid (C6H8O6) | 00.1341 | Table 1: Titration of diluted ascorbic acid Titration number: | Rough | 1 | 2 | 3 | 4 | | Final diji reading/mL | 15.00…show more content…
of mol of NBS used: (5.265*10^-4) * 0.01575 = 8.292*10^-6 mols * Mols of NBS = Mols of ascorbic acid, therefore mols of ascorbic acid = 8.292*10^-6 mols Mass of ascorbic acid in 2.0ml sample * Mass= mol * molar mass * Mass = (8.292*10^-6) * 176 = 0.00146 grams = 1.46 mg Concentration of absorbic acid in 100 ml ribena * 1.46*50 = 73mg/100mL Discussion: Questions: Q1. What volume of ribena would satisfy your minimum daily vitamin C requirement of 60 mg? * 73mg/100ml so for 60 mg * (100/73)*60 = 82.19 mL approx. 82.2 mL Q2: how does your calculated value of mg ascorbic acid per 100mL of ribena compare to the value stated by the manufacturer? * My calculated value is higher than the manufacturer declared value such that the value I obtained was 73mg/100mL while the manufacturer value was 18.2mg/100mL. this great difference in value is due to some inaccuracy in the titration method where more than need solution of NBS was added to the conical flask, this error is quite significant as it will directly and greatly affect the concentration of ascorbic acid in the ribena sample, also error while preparing the diluted solution could have resulted making the concentration of ascorbic acid uncertain, other errors such as measured mass is insignificant as the balance used was quite accurate.

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