Calculations to obtain the amount of Vitamin c:
My data of sodium thiosulfate’s aount for blank and temperatures:
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Titre Values |
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1 |
2 |
3 |
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Avgerage (mL) |
Avgerage (L) |
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blank |
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32,9 |
33,1 |
33,1 |
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33,033 |
0,033033 |
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4 |
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20,4 |
20,5 |
20,5 |
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20,467 |
0,020467 |
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21 |
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20,2 |
20,2 |
20,3 |
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20,233 |
0,020233 |
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40 |
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20,6 |
20,7 |
20,6 |
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20,633 |
0,020633 |
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60 |
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20,6 |
20,7 |
20,7 |
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20,667 |
0,020667 |
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80 |
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21,0 |
21,1 |
21,1 |
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21,067 |
0,021067 |
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100 |
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21,2 |
21,1 |
21 |
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21,100 |
0,021100 |
Volume of Sodium Thiosulfate is 0,033033L
Concentration of Sodium Thiosulfate is 0.089mol/L
Mass of Vitamin C is 176.1gmol-1
Find original amount of I2:
n(sodium thiosulfate)=Concentration (Na2S2O3) x Volume (Na2S2O3)
Equation of reaction between sodium thiosulfate and iodine: 2S2O3+I2->2I-+S4O62-
Get: n(S2O3) : n(I2)
2 : 1
Therefore, n(I2 total) = 0.5 x n(S2O3)
There is using formulas for finding the amount of Viamin C in the solution:
n(Vit C) : n(I2)
1 : 1
n (Vitamin C) = n (I2 reacted with Vit C)= n (I2 total) - n (I2 remaining)
C (Vitamin C) = (n (Vitamin C) x M (Vitamin C))/ V (Vitamin C)
Result:
Table Summarizing the Concentration of Vitamin C:
Temperature(°C) |
Number of Moles (n) of Thiosulfate |
Number of Moles (n) of Iodine |
Number of Moles(n) of Vitamin C (24.84mL) |
Mass (g) of Vitamin C |
Mass (mg) of Vitamin C (24.84 mL) |
Concentration (Vitamin C) in mg/250mL |
4 |
0.001821533 |
0.000911 |
0.0005592 |
0.098478055 |
98.47806 |
991.1237 |
40 |
0.001836367 |
0.000918 |
0.0005518 |
0.09717198 |
97.17198 |
977.9789 |
60 |
0.001839333 |
0.00092 |
0.0005503 |
0.096910765 |
96.91077 |
975.3499 |
80 |
0.001874933 |
0.000937 |
0.0005325 |
0.093776185 |
93.77619 |
943.8022 |
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Temperature (°C) |
Number of Moles (n) of Thiosulfate |
Number of Moles (n) of Iodine |
Number of Moles(n) of Vitamin C (24.79mL) |
Mass (g) of Vitamin C |
Mass (mg) of Vitamin C (24.79 mL) |
Concentration (Vitamin C) in mg/250mL |
21 |
0.001800767 |
0.0009 |
0.0005696 |
0.10030656 |
100.3066 |
1011.563 |
100 |
0.0018779 |
0.000939 |
0.000531 |
0.09351497 |
93.51497 |
943.0715 |