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GC-MS

Discussion in 'Science' started by gasheadruss, Apr 1, 2012.

  1. Has anyone had any inspiration regarding practical ways to teach GC-MS in the new AQA Chemistry 2 spec?

    For mass spectroscopy I was thinking about trying to deflect ball bearings down a slope wih a magnet. Then progressing to different size ball bearings to represent different size ions and somehow measuring to what extent they are deflected.

    In my head this will work but in practice I can imagine it will be fiddly to get right, plus there is the potential for ball bearing related carnage in the lab!

    Unsure on practical ways to tackle the GC part at the moment, but I used one all the time in a previous life so I'm sure something will come to me!

    Any thoughts appreciated!
     
  2. Has anyone had any inspiration regarding practical ways to teach GC-MS in the new AQA Chemistry 2 spec?

    For mass spectroscopy I was thinking about trying to deflect ball bearings down a slope wih a magnet. Then progressing to different size ball bearings to represent different size ions and somehow measuring to what extent they are deflected.

    In my head this will work but in practice I can imagine it will be fiddly to get right, plus there is the potential for ball bearing related carnage in the lab!

    Unsure on practical ways to tackle the GC part at the moment, but I used one all the time in a previous life so I'm sure something will come to me!

    Any thoughts appreciated!
     
  3. ploughlane

    ploughlane New commenter

    Why don't you just do paper chromatography with pens, they'll love it as they probably won't have done it for years and when you discuss how it works you can say that GC works in essentially the same way but has a gas as the mobile phase instead of a liquid.
     
  4. blazer

    blazer Star commenter

    Would it be possible to use different aromas that travel across the lab at different speeds? Spray both into the corner and see which one is detected first?
     
  5. blazer

    blazer Star commenter

    Perhaps the principle could be demonstrated with some sort of variation of the gas race with ammonia and HCl
     
  6. blazer

    blazer Star commenter

    Fill balloons with different gases and place in a breeze. Lighter gases travel faster?
     
  7. It is mass spectrometry.

     
  8. I like this idea [​IMG]
     
  9. Well funny you should say that, that is what I thought, but a check of the AQA documents tell us we're to teach mass spectroscopy!

    I have to find the difference now!
     
  10. Sorry I didn't mean that as a personal attack on you!
    I don't teach AQA so haven't seen this. I'd be questioning them on this.
    I am intrigued to know what "mass spectroscopy" is!
     
  11. No worries!

    Having done a little digging I'm not too clear on the differences, but the general concensus seems to be that the terms are interchangeable.

    I learnt it as spectrometry so that is how I will teach it, just like I teach sulphur with a 'ph' not an 'f'!
     
  12. IUPAC decided it was "sulfur" in 1993 however both are perfectly acceptable haha!
    I was always taught that mass is definitely not a -troscopy as spectroscopy is all about the interaction of matter with energy however spectrometry measures the population of ions with particular masses.

     
  13. I think that GC-MS instruments work with time-of-flight mass specs rather than magnetic sector instruments. I was at a railway station once when I observed a train load of people get out on a neighbouring platform. They were all disgorged at the same time but by the time they got to the ticket barrier they had become widely seperated. What a lovely analogy for chromatography I thought...
     
  14. Beaker

    Beaker New commenter

    Generally the MS in a GC MS system uses a quadrapole system.
     
  15. Moony

    Moony Lead commenter

    What about some sort of angled plain and a load of balls different sizes/masses? Might do the trick.
     
  16. blazer

    blazer Star commenter

    Galileo might disagree!
     
  17. I tried to do this several decades ago, when mass spectro........ was on the Physics syllabus! Deflecting balls by having a magnet was possible- ensuring the slope give sufficient speed whilst the magnet caused deflection but not adhesion was fairly straightforward.
    However, a bigger ball bearing has more mass, so more iron: hence a larger force. This nicely balanced the requirements of Newton's 2nd Law and so all bearings deviated by approximately the same amount. [​IMG] Effectively, iron represents charge, and the "ions" all need the same amount.
    Somehow you need to get more mass without more iron - perhaps embedding them inside other balls (eg golf ball/table-tennis ball) which could then have its mass altered by filling with lead or foam?
    Good luck.
     
  18. To model time of flight mass spec, you can use a hair dryer and blow different size balls along the bench to show that lighter ones travel faster,
     

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