Quantifying Vitamin C Levels in Flavorite’s “Grapefruit Juice”
Analysis of Vitamin C in Juice Product, Data in Slides 12-14
(1) Molarity of Standard Ascorbic Acid Solution
Standard Solution of AA =
(0.05 (g AA/100mL) x 1000mL)/176.1(g AA/mol) = 2.84 x 10-3 M
(2) Molarity of DCP Solution
Standard Solution of DCP =
(2.84×10-5mol DCP/33.57mL DCP) x 1000mL = 8.50×10-4 M in Trial 1
(3) Mass of Ascorbic Acid Titrated in Juice Sample
Ascorbic Acid Mass Titrated in Juice =
((8.5×10-4) mol DCP/1000mL) x (13.61 mL DCP) x (176.1 g AA/mol) x (1000mg/g)) / (5mL juice) = 0.42 mg/mL of Ascorbic Acid in Trial 1
Analysis
This lab focused on determining the amount of Vitamin C in 5 mL of Flavorite’s grapefruit juice by means of oxidation-reduction titrimetry. Our calculations from three trials infer an average of 2.32 milligrams per five mL sample of grapefruit juice. It is important to evaluate our experimental value with the container’s RDA value of 130% in eight ounces, which alleges juice should have 1.63 milligrams per five mL sample. Comparing the experimental value shows a 42% discrepancy, which is not unexpected. In the experiment there were many variables that could have caused slight deviation from the real value: we used many different measurements and reagents to calculate the Vitamin C quantity. On the other hand, we have a handful of data to support our answer; it is too hard to tell if Flavorite’s RDA values are more accurate.
| Average Vitamin C in Flavorite Grapefruit Juice: 0.464 mg/ml |
|
1. Initial Data |
|||||
| Weighing Paper (g) |
0.42 |
Vitamin C solution | |||
| with ascorbic acid |
0.47 |
Volume: | 100mL | ||
| Ascorbic acid (g) |
0.05 |
Molarity: | 2.84×10-3M | ||
| 2. Standardizing the DCP Solution | |||||
| Trials |
1 |
2 |
3 |
||
| Volume of Vitamin C titrated (mL) |
10 |
10 |
10 |
||
| Initial buret reading (mL) |
0 |
0 |
0 |
||
| Final buret reading (mL) |
33.57 |
37.94 |
31.1 |
||
| Moles of Vitamin C titrated | 2.84×10-5 | 2.84×10-5 | 2.84×10-5 | ||
| DCP Solution (M) | 8.5×10-4 | 8.6×10-4 | 9.13×10-4 | ||
| DCP Solution (M)average | 8.77×10-4 | ||||
| 3. Analyzing Vitamin C in Juice Sample | |||||
| Juice Tested: Flavorite Grapefruit | |||||
| Trials |
1 |
2 |
3 |
||
| Volume of juice titrated (mL) |
5 |
5 |
5 |
||
| Initial buret reading (mL) |
0 |
13.61 |
28.62 |
||
| Final buret reading (mL) |
13.61 |
28.62 |
45.11 |
||
| Volume of DCP titrated (mL) |
13.61 |
15.01 |
16.49 |
||
| DCP required (mol) | 1.19×10-5 | 1.32×10-5 | 1.45×10-5 | ||
| Mass of Vitamin C titrated (mg) |
2.1 |
2.32 |
2.55 |
||
| Quanitiy of Vitamin C (mg/mL) |
0.42 |
0.464 |
0.51 |
||
