The label on a carton of a fruit drink lists the mass of vitamin C, C6H8O6\text{C}_6\text{H}_8\text{O}_6C6H8O6, in mg, in a typical serving of 150 cm3150 \text{ cm}^3150 cm3.
A student carries out an investigation to check the vitamin C content in the drink.
Vitamin C is oxidised by iodine according to the following equation:
C6H8O6(aq)+I2(aq)⋯→C6H6O6(aq)+2I−(aq)+2H+(aq) \text{C}_6\text{H}_8\text{O}_6(\text{aq}) + \text{I}_2(\text{aq}) \dots \rightarrow \text{C}_6\text{H}_6\text{O}_6(\text{aq}) + 2\text{I}^-(\text{aq}) + 2\text{H}^+(\text{aq}) C6H8O6(aq)+I2(aq)⋯→C6H6O6(aq)+2I−(aq)+2H+(aq)The student dilutes a 150 cm3150 \text{ cm}^3150 cm3 serving of the fruit drink with water to 250.0 cm3250.0 \text{ cm}^3250.0 cm3 in a volumetric flask.
The student then titrates a 25.0 cm325.0 \text{ cm}^325.0 cm3 volume of this diluted solution with a 1.25×10−3 mol dm−31.25 \times 10^{-3} \text{ mol dm}^{-3}1.25×10−3 mol dm−3 iodine solution, I2(aq)\text{I}_2(\text{aq})I2(aq).
The mean titre of I2(aq)\text{I}_2(\text{aq})I2(aq) is 16.00 cm316.00 \text{ cm}^316.00 cm3.
Determine the mass, in mg, of vitamin C in the 150 cm3150 \text{ cm}^3150 cm3 serving of the fruit drink. Give your answer to 3 significant figures.
199 exam-style questions on OCR A A Level Chemistry Atoms and reactions, covering Atomic structure and isotopes, Compounds, formulae and equations, Amount of substance, Acids, and Redox. Each one has a worked solution and a mark scheme showing where the marks go.