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Hi all,

I have been asked about a prac........it's to do with disease.

Excuse the garbled description, please, but this is how it was explained to me..........

You have about 20 dropper bottles of clear liquid, possibly just water in 19 of them and then a strong base in 1 (the disease).
Each student has a bottle and they proceed to mingle and put drops from their bottles into some of the other peoples bottles, then they add phenolphthalein (?) to see who has been "infected" with the disease and at the end they can trace back to see who the original person was with the disease.

Does anyone know this prac? and if so what chemicals exactly do we use??

Yours in hope

We call it whose got ebola!! 0.001M HCl, 0.1M NaOH as the diseased sample, and phenol red for indicator. They have droppers, swap 1ml with three other people, put in the indicator, infected pink, non infected yellow. Then they try to work out by who swapped with who, which one was diseased Maria

They start out with 5ml of solution!

Super!!
Thanks Maria, much appreciated

We call it the exchanging fluids activity lol.

We give each student two cups each. In one of the cups there's clear liquid and in 3 there's some 0.1M NaOH mixed in. They pour half the solution into the second cup and place on side bench to test later. The students mix liquids with 3 other class members and then test with phenolphthalein.

Extra activity is to try and narrow down who had the original infection (one class got it right!) and then check with the indicator on the 'control' cups.

We've got a similar one called "the spread of HIV". Phenolphthalein is the indicator and we use 0.1M Na2CO3 instead of NaOH.