Assignment:
Vitamin C Content of Juices Report
Procedure 1
Question 1. Calculate the molarity of the ascorbic acid solution:
(a) Mass of ascorbic acid: 0.1g
(b) Moles of ascorbic acid (MW=176.1 g/mol): = 0.00568 mol/L
(c) Volume of solution (mL): 100 ml
(d) Ascorbic acid concentration (mol/L) 5.678 x 10^-3 mol/L???
Question 2. For each titration, record and calculate the following:
|
Trial
|
Volume of Iodine solution (ml)
|
Concentration (Moles/L)
|
|
1
|
8 ml
|
?
|
|
2
|
7.5ml
|
?
|
|
3
|
7.05 ml
|
?
|
Question 3. Calculate the average iodine concentration
using the formula M1*V1 = M2*V2: ?????????
Procedure 2
Question 1. For each titration of the fresh orange juice, record and calculate the following:
|
Trial
|
Volume of Iodine solution (ml)
|
Concentration (Moles/L) of ascorbic acid
|
Concentration (mg/ml) of ascorbic acid
|
|
1
|
7 ml
|
?
|
?
|
|
2
|
6.5 ml
|
?
|
?
|
|
3
|
6.05 ml
|
?
|
?
|
Question 2. For each titration of the week-old orange juice, record and calculate the following:
|
Trial
|
Volume of Iodine solution (ml)
|
Concentration (Moles/L) of ascorbic acid
|
Concentration (mg/ml) of ascorbic acid
|
|
1
|
4 ml
|
?
|
?
|
|
2
|
3 ml
|
?
|
?
|
|
3
|
2 ml
|
?
|
?
|
Question 3. The minimum daily requirement for vitamin C is 60 mg per day. What percentage of this requirement is in one cup (200 mL) of fresh and week-old orange juice?
NEW ?
OLD ?
Question 4. What happens to the ascorbic acid in orange juice over time? (hint: oxygen makes up 20% of our air.)
The ascorbic acid is oxidized by the oxygen, and the concentration decreases over time.