Science for Kids: pH fun

I had the pleasure to go to Laurel Park Elementary school in Apex, NC  to have fun with acids and bases and talk about pH.  There are some fun activities you can do with acids and bases and most of these you can do at home too.

Liquid pH indicators - red cabbage juice

There is this great pH indicator that you can make yourself in the kitchen.   You can boil red cabbage or blend it to collect the juice.   I cheated a little and just bought some cabbage extract in powder form from Amazon.  Just add some powder to water and you have red cabbage juice the easy way.

 For this particular brand you add 1 scoop of powder per 100 mL of water.

Depending on the pH of a liquid you add to the cabbage juice, it will turn different colors.

So we took a few different liquids and added them in order to see a color and then use the color to get an estimated pH..

Liquid pH indicator - bromothymol blue

There is another indicator that is really neat.  It is called bromothymol blue.  When you add just a little bit to water it will be blue since the pH is around around 7 or above.  If you take a straw and blow into the solution it will slowly turn yellow.  The reason is that carbon dioxide from your breath reacts with the water and forms carbonic acid.  Pretty neat stuff!

A dab goes a long way!!

Just blow air into the liquid through a straw

pH indicator strips

Lastly we used pH indicator strips to measure pH.  I just bought these from amazon as well.

We paired the kids up and each pair had 5 tubes.  In these tubes were lemon juice, cherry pepsi, water, baking soda, and windex.    They used a strip for each tube to record the color, match the color to a pH and see if they could figure out what the liquid might be.

These activities are a great way to engage kids while you go over acids, bases, and pH.   It's just another way to make science make sense in a fun way.   Seeing kids getting excited while filling out a science worksheet makes for a good day.   I look forward to seeing what the future holds for these future scientists!