Chromatography.... (?sp) - Help!

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Couldn't work out where to put this, so chose here as we are wanting to learn!!

I remember doing chromatography at school (dots on paper, water etc), but why is it now I am trying to show DD, my black pen is just a black splurge??

She is delighted with herself though - I explained that it was meant to be colourful... left her to it. She called me in showing me one she made of oodles of pens splodged together, so it bleeds out colourful

Was it a permanent ink pen? Washable ones are better because the ink is soluble in water.

Have now foundthis site, where the comments say permanent pens are better!

thanks!

The ink will only separate if you use the right solvent. In your case, the ink is not water soluble. If you tried nail varnish which contains acetone, chances are the ink will separate because the ink is likely to be acetone soluble.

try food colourings, too. You will find that if you run these alongside soluble felt tip that they contain the same dyes (they run up the same rate). Indelible markers and ball piont pens, will need a solvent such as meths, acetone, or as a last resort (and it must be desperate), gin or vodka.

Smarties are quite good for chromatography.

Ooh I forgot about smarties

Need the right solvents and papers to show it best, but if it's a permanent pen you have there then you need an 'organic' solvent (e.g. nail varnish remover, surgical spirit, white spirit etc.). I was showing this to DD a while back with blue food colouring, which is nicely water soluble.

what paper are you using. We used to use the filters that you can get for coffee makers

As to papers, when I taught in school we used filter paper or specialist chromatography paper but homework for the students was to experiment at home, success was achieved with any absorbant material, such as strong tissues, blotting paper, kitchen roll, strips of cotton fabric, cotton string. For colours, try beetroot or blackberry juice to find if the colour is pure (only one blob of colour separates out), or is a mixture (several differently coloured blobs separate out)
Other colour ideas include

1. demonstrating plants taking up water :- put some leafy celery into red/blue food colourng diluted a bit to produce edible stripy celery. Experiment with other plants/flowers
2. Try seeing if the beetroot/blackberry juice changes colour in acid (vinegar or lemon juice) or alkali (baking soda).

Enjoy the experiments, please encourage your kids with science, we need more scientists for our future. Science is fun!

Coffee filters are ideal, but as WG says, anything absorbant should, in theory, work.

I was using thick tissuey nappy liners - they worked perfectly.

I like the celery idea

The celery thing works very well, you can even take out the 'tubes' (xylem) that the water is trnsported in. The movement of water into a plant isn't quite the same as the movement of water into blotting paper though, so you have to make sure the kids don't get confused

OK it depends what age group you are considering, I'm not sure how many of my GCSE students could spot and explain the dfference between osmosis and capillary action. As an 'old school' chemistry teacher, I regret the restrictions on experimenting in school science, (the occsaional smell and bang)and the increasing use of text books rather than hands-on experiments.
From an early age we want our kids to observe and wonder and experiment. Let them hypothesise about what they see, and test their ideas with further experiments.

If you like the celery one, try splitting the celery stem and put each end in a different colour. Try a white/pale coloured flower. I'm sure I have bought flowers colourd by this method.

Ah, carnations!

my nan was a florist and used to dye the tips of the petals of carnations by putting the stalks in food colouring. I used to find it fascinating as a little girl.

Chromatography has fascinated my kids too.
Try ground up grass (you get a lovely orange as well as green), and cheap coloured sweets.
If you put flowers an hour or so in one food colour and then swop to another you can watch the colours mix.
TV screen under a magnifying glass also very good.

DD is only 4, so at the moment she is just interested in making things pretty colours

The doctor's surgery has drips going into 3 plant pots, with 3 different colour liquids so they have colourful plants