Kitchen Art

You may have heard that red cabbage can be used as a litmus test - that the water it is boiled in will change colour if it comes in contact with an acidic or alkaline substance. But have you put it to the test? I decided to try it out after coming across some red cabbage in a supermarket.

Turns out not only does it work very well, but it can also be used to create art works any 4-year-old would be proud of.

Red Cabbage

Lemon juice

Baking Soda

Drawing paper

Some cut up cabbage was boiled on the stove for about 10 minutes with some water. It was then strained through a paper towel, although I don't think the straining through paper was really necessary.

As I had a couple of lemons in the fridge which were past their prime, I squeezed one into a glass and then tested its pH with a meter (I had previously purchased to test the soil in my garden). The lemon juice was on the acidic side. A tablespoon of red cabbage juice (really its purple) was added. This turned the lemon juice bright red.

Next some washing soda was added to a glass and its pH was tested. It was on the alkaline side. After adding some purple cabbage juice and stirring, it changed to a greenish colour.

Purple cabbage juice really does work as a litmus test.

Having some purple cabbage juice, I wondered if litmus paper could be created by painting in on drawing paper? So, I purchased a drawing pad and removed a page. I painted the whole page with the purple juice and then squeezed on some lemon juice, causing the paper to turn reddish. Next, I tried painting on some of the washing soda solution. This caused the paper to turn green. My first 'masterpiece' had been created.

As washing soda is a little too strong to be handled without wearing gloves, I wanted to test baking soda as it is a milder alkali. I also wondered if 'art' could be created by using a stencil and spaying vinegar onto the paper which had been covered with purple cabbage juice. A stencil was cut out of some cardboard.

I painted some more sheets of paper with the purple cabbage juice and let them dry. The next day I used the stencil and sprayed vinegar on to the paper, it turned a darker green. I placed an absorbent paper towel on the artwork after removing the stencil to soak up any excess vinegar.

Next, I painted on some lemon juice - it turned the paper pink.

A baking soda and water paste was made and painted on, it went green - similar to the washing soda, which was also tried. In my opinion using baking soda or lemon juice works best.

I tried testing my garden's soil pH. Some soil was scoop up, mixed with water and left over night. In the morning a couple of litmus strips were placed in the mixture and then allowed to dry. As a control a litmus strip was placed in some water and allowed to dry. As can be seen there may be a slight colour change in the strips placed in the soil water, maybe going slightly a darker green. But to be honest it was a bit hard to tell.

Hydrangeas have a colour which depends on the soil's pH. Red in alkaline soil and Blue in acidic soil. I planted a hydrangea which already had red flowers and noticed the next flower it grew was a lot less red - reflecting that my gardens soil was less alkaline than the soil the plant had originally been grown in.

While you are doing science experiments in your kitchen, heres another one to try:

Mix some cornflower with some water in a bowl. You will notice as more cornflower is added to the water, all of a sudden it will get difficult to stir. Then if you ease up on the stirring, it is easy again. Then try stabbing your finger into the mixture - it will become very resistant, yet you can slowly lower your fingers into the mixture quite easily. Weird! This is due to the nature of the velocity of the cornflower and water mixture; it acts as a non-Newtonian fluid.

If you want to demonstrate how a non-Newtonian fluid behaves with no mess, you can place the mixture into a ballon. To do this:

1. Cut the top off a beverage can with a can opener.
2. Cut the bottom of the can off with a pair of scissors and trim the edge.
3. Stretch the opening of a ballon over the top of the can.
4. Pour in the cornflower and water mixture into the ballon.
5. Tie a knot on the ballon's opening.

Try slowly rolling the ballon on a tabletop, verses rolling it quickly. Try squeezing the ballon slowly verses squeezing it hard and fast. Notice the difference. See how many times you can squeeze the ballon slowly, so your fingers and thumb meet in the middle, within a minute. Compare to when you try to do this hard and fast. I found I could do 57 slow squeezes compared to only 48 fast squeezes.