Weird Science....things we've never seen before..

Mortars and pestles, sand and boiling tubes, ethanol and rubber bungs, funnels and filter papers. Bet you can't guess what my little year 7 class is doing tomorrow?

How about if I give you a clue.............there's two things missing........a red cabbage and a beetroot!


Still no idea? O.K. another clue then.............acids and alkalis will be involved on Friday........ if they do it right tomorrow!

Give up?

They're going to make their own indicators to test various household products on Friday for the presence of acid or alkali.

Half the class will use beetroot and half cabbage. I'll chop it up rough and then they have to grind it up in a little ethanol to get a deep red or purple liquid. Then they have to filter it and refrigerate it overnight, then test it with some sulphuric acid and sodium hydroxide to observe the colour changes and then they can use it to test toothpaste, soap, vinegar, lemon juice, stomach powders and other house hold chemicals to find out which are acids and which are alkalis.

They'll love it and then next week I'll titrate an acid into an alkali to show them all 14 colours on the pH scale and finally I'll use phenolphthalein to show them that lovely test they do on CSI for blood when the end of the cotton bud goes bright pink!

Not a bad set of Chemistry lessons.................for a Biologist!

Das vidanya.