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Discussion in 'Science' started by Jessie1912, Nov 20, 2009.
Would really appreciate it if anyone could suggest something for the above.
Jelly is your best bet and makes the room smell lovely!
1. Temp and dissolving - how long single cube takes to dissolve in 3 temps of water. Fair test same amount of stirring/ water etc
2. Stirring or not use best temp from above and plop jelly cube in and just leave no stirring
3. Surface area - chop 1 jelly cube into 4, another into tiny bits and use a whole one.
You can then get them to think about why jelly doesn't dissolve below a certain temp.
Solvents other than water:
White tile with 3 marks on it (all different colours)
water soluble pen
First whipe gently with cotton wool bud soaked in water, then cotton wool bud soaked in ethanol (meths) then cotton wool bud soaked in acetone. Make sure you do it in that order or nail varnish removes all.
Sorry did not see y 6. Do you do other solvents in KS2???
Hi Thanks very much for your replies, that's great.
The only thing I can see for KS2 Science re dissolving are the usual salt and sugar / water experiments, which is why I asked.
I'm a TA trying to make it a bit more interesting for them, and wondered if anyone had come up with any alternatives!!
I made lava lamps with my Y6 - something like this method:
I used the food colouring and also warm/hot water to speed things up a bit. Once they had all had a go, I got them to explain what was happening in terms of dissolving and insolubility. I was amazed how much they enjoyed it.
Thanks very much! You've all been fab!
Good demonstration for your Yr 6 class.
Make a starch solution - looks clear. You must make it up by mixing starch with cold water into a paste, then adding very hot/boiling water. Leave to cool. (Always use a fresh solution).
Drop iodine, which is a very dark brown colour, from a dropper into the solution - it will disappear instantly with the first few goes. Then it will start to leave a trail of colour, but this will also disappear as you stir it after each addition.
But, and this is the bit that always makes my Yr 6s gasp , when the starch solution is saturated it SUDDENLY turns blue/black.
Iodine is used as a test for starch, if starch is present it turns black.
Starch isn't difficult to get hold of, but you might have to ask a senior school colleague if you can borrow some iodine. Otherwise I am pretty sure you could buy it at the chemist.
Would also advise you to try it out without an audience first so that you have an idea as to how much iodine you would need to drop in before the dramatic change described above.
Thanks a lot!
Great expt this - known as King Kong Hand if you draw hairs onto the glove but its neutralisation not dissolving. The vinegar stops reacting its nothing to do with having a saturated solution