This year, I decided to do away with the traditional spruce Christmas Tree and make my own. Of course being for the chemistry lab it had to be a bit different!
I wanted to make a tree that covered many of the topics covered within the syllabus from year 7 through to the end of upper sixth. Chemistry is such a colourful subject and it seems like a great time to celebrate that. Each item of glassware contains different solutions, chemical tests or indicators and are from practicals that pupils will carry out during Purcell School Chemistry lessons.
The flasks and test tubes contain the following chemicals:
- Tests for Copper (II) ions
Adding dilute ammonia to Copper (II) ions in solution creates a light blue precipitate.
Continuing to add ammonia re-dissolves the precipitate and leaves a deep blue solution.
- Testing for Iron (II)
Adding aqueous sodium hydroxide to a solution containing iron (II) ions forms a green precipitate.
- Testing for aliphatic carbonyls
Adding an aliphatic (non-aromatic) hydrocarbon to Brady’s reagent (2,4-DNPH) produces yellow / orange crystals.
- Testing for aromatic carbonyls
Adding an aliphatic (non-aromatic) hydrocarbon to Brady’s reagent (2,4-DNPH) produces red crystals. (the colour is only a general guide and not really conclusive)
- Different pH solutions
Using universal indicator in strong acid, weak acid, neutral solution, weak alkali and strong alkali produces a lovely array of colours
- Phenolphthalein indicator
Adding Phenolphthalein to a very weak solution of sodium hydroxide turns it bright pink!
We use this indicator in many acid – alkali titrations as it has a great colour change that is very clear and turns very quickly.
- Methyl orange indicator
Add methyl orange to an acid and it turns a shade of red
Add methyl orange to an alkali it turns yellow / orange
Methyl orange is an excellent acid – weak base indicator as it changes colour at roughly pH3
- Golden Rain
Lead nitrate + potassium iodide.
You can find out more about all of these by visiting the analytical chemistry section of chemstuff.
Anyway, I think the end result is almost as exciting as the chemistry behind it. Please tweet @chemstuff if you have ideas for more branches on the tree or even better if you have pictures of your own!
If you try any of these out, please ensure that you consult CLEAPSS before starting any of them. The photo’s were very kindly taken by C Hayes.