Barney Juice...

Last week on science we learned about pH scales. But today we are going to make a purple cabbage indicator that will test the acidity or alkalinity of white vinegar and washing powder. The indicator is neutral and has a pH scale of 7. I was grouped up with Lars and Blake, we worked pretty well during the experiment.

This is the procedure of the experiment:

• 1 Peel off three or four big cabbage leaves and put them in a blender filled half full with water. Blend the mixture on high until you have purple cabbage juice.

• 2 Pour the purplish cabbage liquid through a strainer to filter out all of the big chunks of cabbage. Save the liquid for the experiments to follow.

• 3 Set out three beakers, side by side. Fill each glass three-quarters full with cabbage juice.

• 4 Add a little vinegar to the first beaker of cabbage juice. Stir with stirring rod and watch the colour change.

• 5 In the second beaker, add a little laundry detergent and stir.

• 6 Take a photo of your 3 beakers side by side.

There was also a couple of questions before we did the experiment, and here are my answers.

What colour do you think white vinegar will turn the purple cabbage indicator?

I think that it the purple cabbage will turn into a colour red. Or close to red.

Why do you think this? Because the vinegar will take the colour purple and lighten the colour and the vinegar are acidic.

What colour do you think the washing powder will turn the purple cabbage indicator? I think it will be still purple or it will be red again.

Why do you think this? Because washing powder is alkaline.

Reflection:

Were your answers right or wrong? Some of it was right but not all of them.

What number do you think the white vinegar would be on the pH scale? pH 3 or 2

What number do you think the washing powder would be on the pH scale? pH 8.5 or 9.5