Vitamin C
Estimating the Vitamin C Concentration in Fruit Juices: A Redox Titration
Prelab Assignment – Please turn your answers in on GaView prior to lab
1. How will you prepare a .02% (m/v) NBS solution? Calculations should be in your notebook before arriving to lab.
2. Provide the structure of vitamin C in its reduced form (ascorbic acid), its ionized form (ascorbate ion- this is at equilibrium with reduced form when dissolved), and its oxidized form (dehydroascorbate).
3. Why do you think that the indicator solution contains acetic acid? How might its absence affect the titration?
4. How much vitamin C has been reported in the fruits that we will be using in today’s lab? Cite your reference. Be sure to list all units on your values. Do not report % of RDA per serving.
Estimating the Vitamin C Concentration in Fruit Juices: A Redox Titration
Learning Outcomes * Acquire laboratory skill in redox titration. * Acquire laboratory skill in the use of a glass pipet. * Standardize a solution to be used as a titrant. * Conduct multiple titrations to determine an average concentration of Vitamin C present in a fruit juice sample.
Introduction
In this lab, each pair of students will standardize an N-bromosuccinimide (NBS) solution with a known amount of Vitamin C and use this standard solution to determine the amount of Vitamin C present in a fruit juice sample.
Background
Vitamins are essential micronutrients in our diet. We need them in small amounts to stay healthy. Although they were originally thought to be “vital amines,” we now know that there are two categories of vitamins: fat-soluble (A, D, E, K) and water-soluble (the B complex and C). Most vitamins act as cofactors with metabolic enzymes to maintain our life processes.
Vitamin C, or ascorbic acid, is a water-soluble molecule that acts as an antioxidant, i.e. if oxidizing agents attack a cell, then the vitamin C acts as a target in place of another more
Prelab Assignment – Please turn your answers in on GaView prior to lab
1. How will you prepare a .02% (m/v) NBS solution? Calculations should be in your notebook before arriving to lab.
2. Provide the structure of vitamin C in its reduced form (ascorbic acid), its ionized form (ascorbate ion- this is at equilibrium with reduced form when dissolved), and its oxidized form (dehydroascorbate).
3. Why do you think that the indicator solution contains acetic acid? How might its absence affect the titration?
4. How much vitamin C has been reported in the fruits that we will be using in today’s lab? Cite your reference. Be sure to list all units on your values. Do not report % of RDA per serving.
Estimating the Vitamin C Concentration in Fruit Juices: A Redox Titration
Learning Outcomes * Acquire laboratory skill in redox titration. * Acquire laboratory skill in the use of a glass pipet. * Standardize a solution to be used as a titrant. * Conduct multiple titrations to determine an average concentration of Vitamin C present in a fruit juice sample.
Introduction
In this lab, each pair of students will standardize an N-bromosuccinimide (NBS) solution with a known amount of Vitamin C and use this standard solution to determine the amount of Vitamin C present in a fruit juice sample.
Background
Vitamins are essential micronutrients in our diet. We need them in small amounts to stay healthy. Although they were originally thought to be “vital amines,” we now know that there are two categories of vitamins: fat-soluble (A, D, E, K) and water-soluble (the B complex and C). Most vitamins act as cofactors with metabolic enzymes to maintain our life processes.
Vitamin C, or ascorbic acid, is a water-soluble molecule that acts as an antioxidant, i.e. if oxidizing agents attack a cell, then the vitamin C acts as a target in place of another more