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)?
b. What quantity of juice will provide the RDA amount of vitamin C (mL)?
To determine the concentration of vitamin C in the juice, we first need to calculate the number of moles of iodine consumed during the titration. From there, we can relate the moles of iodine to the moles of vitamin C present in the juice sample.
a. To calculate the concentration of vitamin C in the juice (mg/100 mL), follow these steps:
Step 1: Determine the number of moles of iodine consumed.
The volume of iodine solution used is 9.85 mL, which is equal to 0.00985 L (since 1 mL = 0.001 L).
The molarity of the iodine solution is not provided, so we need additional information. If you have the molarity of the iodine solution, you can proceed to Step 2. Otherwise, you'll need to determine the molarity by performing a standardization titration of the iodine solution with a known reductant.
Step 2: Relate the moles of iodine to the moles of vitamin C.
The balanced chemical equation for the reaction between iodine and vitamin C is:
C6H8O6 + I2 -> C6H6O6 + 2HI
From the stoichiometry, we can see that one mole of iodine reacts with one mole of vitamin C. Therefore, the number of moles of iodine consumed will be equal to the number of moles of vitamin C present in the sample.
Step 3: Calculate the concentration of vitamin C in the juice.
The concentration of vitamin C can be calculated using the formula:
Concentration (mg/100 mL) = (moles of vitamin C/Moles of juice) x 100 x Molar mass (mg/mole)
In this case, since we are given the volume of juice (100 mL), we can simply substitute it into the formula:
Concentration (mg/100 mL) = (moles of vitamin C/0.1 L) x 100 x Molar mass (mg/mole)
b. To calculate the quantity of juice that will provide the Recommended Daily Allowance (RDA) amount of vitamin C:
Step 1: Determine the amount of vitamin C needed.
The RDA amount of vitamin C varies by age, sex, and other factors. Let's assume, for example, that the RDA amount of vitamin C is 90 mg/day.
Step 2: Use the concentration of vitamin C calculated in part a to find the volume of juice required.
The equation for volume and concentration is:
Volume (mL) = (Amount of vitamin C needed (mg)/Concentration (mg/100 mL)) x 100
By substituting the values into the equation, you can calculate the quantity of juice needed to provide the RDA amount of vitamin C.
Please keep in mind that the above explanation provides a general guideline for solving the problem. Actual calculations may require specific values and considerations.
To calculate the concentration of vitamin C in the juice and the quantity of juice required to meet the Recommended Daily Allowance (RDA) of vitamin C, we need to follow these steps:
Step 1: Find the concentration (in mol/L) of the iodine solution.
Step 2: Convert the volume of iodine solution used (9.85 mL) to moles of iodine.
Step 3: Determine the stoichiometry of the reaction between iodine and vitamin C.
Step 4: Convert moles of iodine to moles of vitamin C.
Step 5: Convert moles of vitamin C to milligrams (mg).
Step 6: Calculate the concentration of vitamin C in mg/100 mL of juice.
Step 7: Calculate the quantity of juice required to meet the RDA of vitamin C.
Now, let's proceed with the calculations step by step.
Step 1: Find the concentration of the iodine solution.
The information provided does not mention the concentration of the iodine solution. Hence, we are unable to calculate the vitamin C concentration in mg/100 mL of juice (part a).
Step 2: Convert the volume of iodine solution used to moles of iodine.
Given that 9.85 mL of the iodine solution was used, we need to convert this volume to moles of iodine using the solution's concentration.
Since the concentration of the iodine solution is not provided, we cannot proceed further to calculate the moles of iodine (part a).
Step 3: Determine the stoichiometry of the reaction between iodine and vitamin C.
The stoichiometry of the reaction between iodine (I2) and vitamin C (ascorbic acid) is:
C6H8O6 + I2 → C6H6O6 + 2HI
Step 4: Convert moles of iodine to moles of vitamin C.
Since we do not have the moles of iodine, we cannot calculate the moles of vitamin C.
Step 5: Convert moles of vitamin C to milligrams.
Without the moles of iodine and vitamin C, we cannot calculate the milligrams of vitamin C.
Step 6: Calculate the concentration of vitamin C in mg/100 mL of juice.
Since we do not have the necessary information, we cannot calculate the concentration of vitamin C in mg/100 mL of juice (part a).
Step 7: Calculate the quantity of juice required to meet the RDA of vitamin C.
Without the concentration of vitamin C, we cannot calculate the quantity of juice required to meet the RDA (part b).
In conclusion, we are unable to calculate both the concentration of vitamin C in mg/100 mL of juice (part a) and the quantity of juice required to meet the RDA of vitamin C (part b) due to insufficient information.