Plants from Balclutha Primary School science garden.

Chemistry outreach spent a session with room 10 and there teacher Jenny Harris looking at the colours we could make using plants from the science garden and some dilute acid and base.

A range of flowers we used

 The plants have one colour in acid and another in base but by mixing the solutions up we found they could create a range of colours.

Ladies Mantle

 Most of these plants worked nicely, although during the course of the experiment some colours were made and then used up ...

purple iris

Rhododendron

Rhododendron has a different dye than most of the other plants so it can only give a range of reds/ornages rather the the variety of other flowers.

Azalea

Lavender 

The colours from lavender didn't come out too well but in real life there was a lovely range of blue/green and green colours.

Purple pansies

Plant pH indicators

So here's a little project we're starting and anyone can join in, maybe as a holiday project.

The juice of some plants like red cabbage change colour when you add acid or base to them as you can see from the photos.

 We'd like to find a native NZ plant (or one from somewhere else around the world) that can be used in place of cabbage.

If you are interested, you will need to look for red/purple flowers/leaves and put them in some nearly boiling water and get a nice dark coloured solution, like the purple one in the photo.
Then get something like an ice cube tray and put some of the coloured water into the holes.
To one hole add some acid, into another add some base. In the photo of cabbage water above the acid is red and the base is green. The solutions we used year with Waitahuna school were 0.1 M hydrochloric and and sodium hydroxide but these are usually available at home so you could use white vinegar and baking soda (sodium carbonate) to get the colours.
By experimenting with mixtures of acid and base you can get a range of colours like these:

If you send a picture of the colours you get with vinegar, water and baking soda to us I will post them on this page with your name.

Thank you to Gloria Penrice and the kids from Waitahuna school senior class for the work they did on this with us. ESPECIALLY thank you to Jenny Harris from Balclutha Primary school for her work on setting these experiments up as part of her Royal Society of New Zealand teacher fellowship.