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Homework Help: IB Chemistry Extended Essay help

  1. Apr 30, 2012 #1
    1. The problem statement, all variables and given/known data
    For my IB extended essay I want to determine the quantity of salt in comercial popcorns, and
    analyze if this amount of salt consumption is bad for one's health. I've made my investigation, and read that the levels of salt in these popcorns are quite high, and in the long run can cause many health problems such as high blood pressure and hearth disease. I want your help in choosing the best method to prove this, please, any idea can help.

    2. Relevant equations
    I don't know any relevant equations for this, but I do know that sodium chloride's chemical formula is NaCl, but this is just common knowledge.

    3. The attempt at a solution
    My hypothesis is that the sodium levels will be higher than the recommended daily consumption.
  2. jcsd
  3. May 2, 2012 #2
    You will not be able to prove this. Even a link between salt and heart disease requires massive clinical trials.

    Your best bet would be a literature search and review. You can make some interesting propositions based on first hand chemistry/biology research but any link to human health would be a complete guess.
  4. May 2, 2012 #3
    Are you trying to prove that there is a link between salt intake and heat disease? If you are trying to do this as SasQuach said you will have a very hard time doing it :S

    Or are you trying to work out how much salt is in popcorn?

    To work out the amount of NaCl in popcorn will be much easier though.

    If it was me doing it I would first weigh out x mg amount of popcorn. Then break up the popcorn into a fine powder and attempt to dissolve as much of it as possible in water (well not quite water actually a buffer solution, TISAB), to get the NaCl in a solution.

    In solution the NaCl will dissociate into Na+ and Cl- ions using an ion selective electrode (Na+ selective or Cl- selective) we can get an output that relates to the amount of NaCl in the solution.

    Now after you have done this you will need to construct a calibration graph. These are quite easy to do although a little bit time consuming. You will need to make up a series standard samples of NaCl, in other words you need to add known amounts of NaCl to a known amount of TISAB so you have a series of NaCl samples of known concentration. Use the ion selective electrode to get a reading relating to each of these samples.

    You can now make your calibration graph plot the output from the ion selective electrode, normally in mV (i think), on the y axis. Against the concentration of NaCl, you can then draw a line of best fit.

    Using the line of best fit of the calibration graph and the output you got from your unknown sample you will be able to calculate the concentration in your unknown sample. (y=mx+c.... concentration = (output of unknown - constant of line of best fit)/gradient)

    From the constant you can then work out the number of moles of NaCl in your x mg of popcorn. From number of moles you can work out the weight of NaCl in your x mg of popcorn sample. =)

    Ofc this could be extrapolated to work out the weight of NaCl in an average sized bag of popcorn if doing that bare in mind you will have to do the above for more than one test sample otherwise your errors will be HUGE! (note you can use the same calibration graph for each new sample)

    Hope that helps if you were going to go a head and base your essay on this I would suggest you do some reading on Ion selective electrodes.

    Right I was going to include some useful links but site won't let me :( Sorry
  5. May 31, 2012 #4
    Thank you very much! Yes SasQuach, I realized that I cannot directly prove the link between this levels and their effects on our health, but as Tecless said, the main idea that I wanna do my extended essay about is how much salt is on popcorn(:
    As to your explanation Tecless, it was pretty good and easy to understand, thank you! Now I will do my research in what you told me and I hope I do well:B Don't worry about the links, the info is more than enough(:
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