N5 Chemistry

O

Innocent smooth juice:

  • 22 mg/100ml

  • https://www.innocentdrinks.co.uk/things-we-make/juices

Tesco juice:

  • 30 mg/100ml

  • https://www.tesco.com/groceries/en-GB/products/255595843

Tropicana:

  • 28 mg/100ml

  • https://www.tropicana.co.uk/juice/orange-smooth

Supporting information

Oxidation: https://www.bbc.co.uk/bitesize/guides/zyq22hv/revision/4

Redox: https://www.bbc.co.uk/bitesize/guides/ztkdd2p/revision/5

Procedure:

  1. Rinse 25cm3 pipette with orange juice sample 1.

  2. Pipette a 25cm3 orange juice into a conical flask.

  3. Add ~1cm' of 1% starch solution and 150cm3 of distilled water to the conical flask

  4. Rinse a 50cm3 burette with a little 0.005molL-1 iodine solution

  5. Fill the burette with 0.005molL-1 iodine solution.

  6. Place the conical flask containing the vitamin C sample directly underneath the burette and record the initial reading on the burette.

  7. Add the iodine solution from the burette into the conical flask with swirling and continue adding it until the first permanent trace of a dark blue-black colour appears.

  8. Record the final reading on the burette.

Alcohol(1st and 2nd) oxidising agent:

  • - Hot copper(Il) oxide, black to brown.

  • - Potassium (acidified) dichromate (VI), orange to green.

Aldehyde oxidising agent (test for aldehyde):

  • - Fehling's solution, blue to a brick red precipitate

  • - Tollens' reagent, clear colourless to a silver mirror

    Oxidising agent (redox titration):

  • - Permanganate, purple to colourless (self indicating)