Recent content by Medchemist

  1. M

    testing in schools

    Has anyone who has had covid (confirmed by PCR) given the test a go? In theory it should be positive. I was isolating after a +ve PCR test on the 5th, I'm starting my first shift playing med lab technician tomorrow, but yesterday they asked if I wanted to take a test when if I said yes I'd be...
  2. M

    Can I be asked to supervise keyworker and vulnerable children?

    I never said it was fair. I didn't know about the clause being tested in court, that's interesting and handy as well as the insurance aspect - I'll have to remember those, thank you for your wisdom.
  3. M

    Lubricating glass joints

    I second purple cat. I have a masters in chemistry and the grease was only for when you needed to put the apparatus under vacuum as the joints leak air otherwise. The profs would take marks off if you used grease and it wound up in your product! You clean joints to within an inch of their...
  4. M

    Can I be asked to supervise keyworker and vulnerable children?

    To supervise children you need no qualification, I used to be a cover supervisor and do not have qualified teacher status (QTS), just my chemistry degrees. To teach children you need to have QTS in state schools/academy schools, the only exception being independent schools. The term...
  5. M

    Used sand

    React any excess acid with copper carbonate/oxide then filter off the excess solid and evaporate to get copper sulfate crystals.
  6. M

    safety goggles and Demos

    Personally I would say that kids and teachers alike should get into the habit of wearing them when doing almost any experiment as it's such a simple measure that can save such a delicate and useful sense. My eyes have been saved 3 times in my 6 years of being a chemist from a injury that would...
  7. M

    Determination of the order of a reaction

    Sulfuric acid is and oxidising agent only in high concentration and I'm going to assume your bench acids are correctly made. The most likely culprit is oxygen dissolved in solution, if the water you use sits around for a while it will absorb atmospheric oxygen which will in turn start...
  8. M

    Sodium thiosulphate

    Bet that smells nice. I would refrain from using thiosulfate because it is a source of sulfur that bacteria can use, the byproduct of which is hydrogen sulfide which will make the situation far more smelly. Hypochlorite (bleach) is far from stable, especially when dry and in a day or two it...
  9. M

    Column Chromatography

    SO, I decided to give the mini column a go for the first time in ages... I tried talc but thats too fine and clogged the whole thing up - cotton wool (cellulose) jammed in and packed in with a capillary tube works well for separating food colouring using acetone/ethanol (roughly 10% ethanol)...
  10. M

    Bacteria for practicing

    I would suggest Lactobacillus casei from some Yakult or Actimel, streak some of that on nutrient agar and then make a broth/slant from a isolated colony. I would wipe the foil lid and neck of the bottle with some 70% ethanol to kill any nasty stuff on the outside that might contaminate when you...
  11. M

    Does propanone go 'off'?

    This is a good point, although it begs the question which godless soul put the washings back in the bottle :eek:
  12. M

    Lead Acetate paper for Hydrogen Sulphide detection

    https://www.sigmaaldrich.com/catalog/product/sial/37104?lang=en&region=GB Under "General Description" it says that it is typically prepared by soaking filter paper in 1% lead acetate solution followed by drying.
  13. M

    rescuing wet chlorides

    They would still make the right colour if they've just taken in some water. You'll want to keep the stock bottle pure though so perhaps chisel some small lumps out and give a small lump of each salt in each 'kit' maybe with a pestle and mortar as a hint.
  14. M

    Testing Unknown Solutions and Solids

    Identifying unknowns is tricky even with a mass spectrometer, IR, NMR etc. In a school lab it's almost impossible to identify anything beyond common metal salts. Find a waste disposal company that will run tests or an analytical lab that will, it's expensive but really the only sensible option
  15. M

    Column Chromatography

    The first issues I can see with this is the volume of solvent needed (and needing disposal) and use and disposal of silica which is basically asbestos dust from your lung's point of view. You could try a miniaturised column in a pasteur pipette (look up microscale column chromatography) using...
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