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Homework Help: Extract these materials from a mixture?

  1. Jul 11, 2010 #1
    I have a number of materials all mixed together in a beaker, my task is to extract each material individually, and get the weight of those materials.

    The materials in the beaker are:
    -Olive Oil
    -Copper 'bits' about the size of rice grains
    -Beach Sand
    -Iron Filings
    -Gravel - pebbles and broken rock
    -Sodium Chloride
    -Calcium Carbonate Powder

    I have made this preliminary method:

    1. Add 200mL water
    2. Place the beaker in the fridge overnight
    3. Scoop the now solidified oil off the top of the mixture. Extract any remaining with a pipette if necessary.
    4. Pour the mixture through the smallest sieve, leaving the solids in the sieve and water in a beaker. Scrape the solids into shallow tray.
    5. Evaporate the water using a Bunsen Burner to leave the Sodium Chloride behind.
    6. Use a large sieve to filter the smaller solids and leave the gravel behind.
    7. Pour the remaining solids into a shallow tray, and add 200mL water.
    8. Use a magnet, moving slowly left to right over the mixture in the shallow tray to extract all the iron. Repeat this for as long as necessary, shaking the mixture in the tray between swipes.
    9. Sieve out the copper from the sand and calcium using the middle sized sieve.
    10. Weight this amount.
    11. Add 100mL of water to the sand & calcium carbonate.
    12. Add HCL to the solution, causing calcium carbonate to dissolve.
    13. Filter out the sand.
    14. Weigh the sand and calculate the difference from the previous amount.

    I know some of that probably won't work. How can I improve it? What would you do?

    Thanks a lot! :)
  2. jcsd
  3. Jul 12, 2010 #2
    I'm getting desperate, can anyone give any input?

    For instance, should I wait for the oil to rise to the top initially before putting it in the fridge? Will the fridge technique work?

    I only have one shot at this! Help! :)
  4. Jul 12, 2010 #3
    If the limestone is very porous, you may have oil trapped within the pores. Have you considered using a volatile organic solvent to extract the oil, before adding the water?

    Also, when drying solid samples like the sand, you will want to dry the sample, weigh it, dry it again, and weigh it again, etc.--until the measured weight is the same for two consecutive measurements.

    Speaking of residual liquid trapped in pores (or between grains), you should wash the sample multiple times when you're trying to dissolve the sodium chloride. There will always be some trapped liquid before you dry the solids, and you want to dilute the NaCL as much as possible, to reduce the amount remaining in the sample.
    Last edited: Jul 12, 2010
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