How do scientists find out what something contains?

  1. How do scientists find out what something contains, like a liquid, or a mushy ball of crushed leafs. Do they do a bunch of tests, or do they put it through a machine which then gives them the answer. Also how do they know that what they`ve got after an reaction is actually what the wanted and not some rare phenomena.
  2. jcsd
  3. jfizzix

    jfizzix 468
    Science Advisor
    Gold Member

    A lot of times, scientists can figure out what something contains by burning a sample up and looking at the color spectrum of the atoms in the vapor.

    The way this works is that over time a lot of scientists have performed these tests on specially made samples of pure substances, and use those color spectra as a reference written in books or websites.

    These color spectra are unique to each kind of atom and molecule; they are an optical fingerprint.

    That way, when they burn up an unknown sample, they can figure out if it has the spectrum of one of the substances they know about (or a mixture of a few different ones).
  4. turbo

    turbo 7,063
    Gold Member

    If you're concerned with the content of a solution, look up Qualitative Analysis. Quantitative Analyses is concerned with how much stuff there is in a sample. Good luck.
  5. Borek

    Staff: Mentor

    Google for GCMS, FTIR spectroscopy, UV-Vis spectroscopy, NMR spectroscopy, AAS (Atomic absorption spectroscopy) and so on. In the case of a mixture typical approach is to separate compounds first, identify them second (although not always - in AAS we can try to analyze everything at once, but AAS doesn't tell us much about compounds present, just spits out elemental composition).

    There is no single procedure that will work for every sample. Besides, especially when it comes to biological materials which are insanely complicated mixtures, we are rarely interested in knowing exact composition, we are more interested in knowing how much of a particular compound is present.
  6. I will take a look at that, thanks :)
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