. A sample of fresh grapefruit juice was filtered and titrated with the above I2 solution. A 100 mL sample of the juice took 9.85 mL of the iodine solution to reach the starch endpoint.
a) What is the concentration of vitamin C in the juice in mg vitamin C/100 mL of juice (mg/ 100 mL)?
And what, pray tell, is the molarity of the I2 solution used. As posted this is not workable.
To determine the concentration of vitamin C in the juice, we need to calculate the number of moles of iodine used in the titration.
First, we need to convert the volume of iodine solution used (9.85 mL) to liters:
9.85 mL = 0.00985 L
Next, we can use the balanced equation between iodine and vitamin C to find the moles of iodine used. The balanced equation is:
C6H8O6 + I2 -> C6H6O6 + 2HI
From the equation, we can see that 1 mole of vitamin C reacts with 1 mole of iodine. This means that the moles of iodine used in the titration are equal to the moles of vitamin C in the juice.
The molarity of the iodine solution is given as 0.020 M. Using this information, we can calculate the number of moles of iodine:
moles of iodine = volume of iodine solution (L) x molarity of iodine solution (M)
= 0.00985 L x 0.020 M
= 0.000197 moles of iodine
Since the moles of iodine are equal to the moles of vitamin C, we can calculate the concentration of vitamin C in the juice per 100 mL.
moles of vitamin C = 0.000197 moles
Now, we need to find the mass of vitamin C in mg:
mass of vitamin C = moles of vitamin C x molar mass of vitamin C (in g) x 1000 (to convert to mg)
The molar mass of vitamin C is 176.12 g/mol.
mass of vitamin C = 0.000197 moles x 176.12 g/mol x 1000 mg/g
= 34.68 mg
Finally, we can calculate the concentration of vitamin C per 100 mL of juice:
concentration of vitamin C = mass of vitamin C / volume of juice (in mL) x 100
Given that the volume of the juice used in the titration is 100 mL:
concentration of vitamin C = 34.68 mg / 100 mL x 100
= 34.68 mg/100 mL
Therefore, the concentration of vitamin C in the juice is 34.68 mg/100 mL.
To calculate the concentration of vitamin C in the juice, you need to know the volume of iodine solution (I2) used and the concentration of the iodine solution.
First, let's calculate the number of moles of iodine (I2) used.
From the given information, a 100 mL sample of juice took 9.85 mL of the iodine solution to reach the starch endpoint. This means that the volume of iodine solution used is 9.85 mL.
Next, we need to determine the concentration of the iodine solution. The concentration of the iodine solution is not given in the question, so you will need that information to proceed further.
Once you have the concentration of the iodine solution in moles per liter (M), you can calculate the moles of iodine used by multiplying the concentration (M) by the volume used (in liters).
Now, since we know that vitamin C, ascorbic acid (C6H8O6), is oxidized by iodine (I2) during this reaction, we can use the balanced chemical equation to relate the moles of iodine used to the moles of vitamin C in the juice.
The balanced chemical equation is:
C6H8O6 + I2 → C6H6O6 + 2HI
From the balanced equation, we can see that one mole of vitamin C reacts with one mole of iodine. Therefore, the moles of iodine used are equal to the moles of vitamin C present in the juice.
Finally, we can calculate the concentration of vitamin C in the juice by dividing the moles of vitamin C by the volume of the juice sample (100 mL) and converting to the desired units (mg/100 mL).