Igcse Model Questions Vol1 2024 Biology Question 3

Practice practical question 3 from the 2024 Igcse Model Questions Vol1 Biology examination. This question covers Nutrition .

Igcse Model Questions Vol1 2024 Biology Practical

Topic: Nutrition

Question 3 IGCSE_MODEL_QUESTIONS_VOL1 • 2024 • BIOLOGY • practical

A group of students carried out an experiment to determine the amount of vitamin C in orange juice using the 2,6‑dichlorophenolindophenol (DCPIP) titration method. The DCPIP solution was standardised to a concentration of 0.010 mol L⁻¹. A 10.0 mL sample of freshly squeezed orange juice was titrated, and the average volume of DCPIP required to reach the endpoint was 12.5 mL. A blank titration (juice replaced by distilled water) required 1.0 mL of DCPIP.

Question Parts

( a )

Calculate the mass of vitamin C (ascorbic acid) present in the 10.0 mL juice sample. (Molar mass of ascorbic acid = 176.12 g mol⁻¹; 1 mol DCPIP reacts with 1 mol vitamin C.)

( b )

Express the vitamin C content as milligrams per 100 mL of juice.

( c )

Identify two possible sources of systematic error in this experiment and suggest how each could be minimised.

( d )

Explain why the blank titration is necessary.

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About This Question

This is Igcse Model Questions Vol1 2024 Biology Question 3. It is one of the practical questions from the 2024 Igcse Model Questions Vol1 Biology examination.

The question covers Nutrition .

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