Science Smarts: National Chemistry Week

By Patty Rooks on October 15, 2022.

This past week we celebrated National Chemistry Week. I may be a bit biased (and do not tell others) but I think that Chemistry is one of the more exciting sciences! Perhaps it is because the effects are so instantaneous – science literally unfolds before your eyes and often in amazing ways. Of course, that means that we have to do a Chemistry experiment right here… it will be safe though, do not worry. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

•

One head of purple cabbage

• Distilled water

• Kettle

• Grater

• Spoon

•

Large glass bowl (heatproof)

• Mesh strainer

•

Storage container/small dropper bottles

• Plate

Procedure

1. Fill the kettle with water and plug it in to boil.

2. Please ask an adult to help you with this step. Using the grater shred the cabbage into smaller pieces.

3. Place the shredded cabbage into the bowl.

4. Pour the boiling water over the cabbage. Make sure it is entirely covered with water.

5. Set the mixture aside for at least 30 minutes.

6. Observe. What is happening?

7. Once the mixture is cool and the water is a nice deep purple colour, strain the cabbage out of the liquid.

8. Discard the cabbage.

9. You can put the indicator into small dropper bottles or in a large container and use a medicine dropper to dispense the liquid.

10. Test for the presence of acids and bases in some common household items. A suggested list is provided below:

What can I test?

1* vinegar

2* baking soda solution (be sure to use distilled water to make)

3* lemon juice

4* club soda

5* ammonia

6* tap water

7* milk

8* pop

9* egg whites

10* dish soap

11* liquid hand soap

12* anything else you can think of

11. Take a small amount of the liquid that you would like to test and place it on a plate.

12. Add a couple of drops of the cabbage indicator.

13. Observe what colour the solution turns.

What is going on?

You took a simple household substance and made an acid base indicator. You can purchase expensive acid base indicators from chemical supply companies, but that is not necessary. Purple Cabbage Juice is an amazing inexpensive chemical indicator.

An “indicator” is a substance that turns colour in the presence of acids and/or bases. For instance, when you added the vinegar (acetic acid) to the cabbage juice, it turned red. The darker the red colour indicates that it is a stronger acid.

When you added the baking soda solution (sodium bicarbonate) which is a base, the indicator should have turned green. Pure or distilled water, which is neutral (neither an acid nor a base) will not have turned any colour, it should have stayed purple.

In our kitchen at home we can find many acids and bases. Lemons, limes, apple juice, coffee and of course vinegar are all acids. Baking soda and egg whites are basic. Can you think of any others?

Mark your calendars… our annual Family Science Olympics returns Saturday, Oct. 29 from 10 a.m. to 3 p.m. at Medicine Hat College. Hands-on science activities and prizes for ALL ages. See you there!

Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403-527-5365, email: praxis@praxismh.ca

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