By Lisa Justice
Scientists use special pH paper to determine if a substance is acidic or not. But you can make your own kind of pH paper in your kitchen and use it to observe your own chemical reactions.
You will need: blackberries, water, dish soap, vinegar, three small bowls, scissors, paper towels, construction paper and a zip-lock bag.
First, put all the blackberries and a small amount of water in the zip-lock bag. Zip it tight so it won’t spill. Then use your fingers to squish the bag and mash up the berries until you have a bag full of berry juice.
Pour the berry juice out into a bowl and cut your construction paper into strips or any shape you like. One at a time, dip your pieces of construction paper into the berry juice. Be sure to cover the entire piece of construction paper.
Once your construction paper is completely coated in berry juice, lay it out to dry on a paper towel. You can pick off any seeds or bits of fruit that may have gotten stuck. When the construction paper is completely dry, it’s ready to use.
Pour a small amount of water in one of your other bowls and add a couple of squirts of dish soap. Pour a small amount of vinegar in your last bowl.
Now, choose two pieces of berry-soaked construction paper. Dip one piece about halfway into the bowl of soapy water. Dip the other one about halfway into the bowl of vinegar.
As you lay these pieces of construction paper on a fresh paper towel to dry, think about what you think might happen next. What do you expect? Do you think the soapy water will have the same effect as the vinegar, or a different effect? What would happen if you dipped the same piece of construction paper into the soapy water and then into the vinegar? Or vice versa?
When the construction paper is dry, take a look. What do you observe? Is it what you expected? What caused the changes you’re seeing?
Blackberries, like most berries, contain a chemical compound known as anthocyanin. Anthocyanin compounds turn red when they come into contact with acidic substances and blue when they meet bases. Vinegar is very acidic, but soapy water isn’t, so when your berry-soaked construction paper came into contact with these different liquids, it reacted differently.
What would happen if you tried your berry-soaked construction paper in other liquids like plain water, milk, fruit juice or soda? Can you think of a way to use your knowledge of acids, bases and anthocyanin compounds to make some art? How about dipping a cotton swab in an acidic liquid and using it to draw on your berry-soaked construction paper?
“Like” Explorit on Facebook to share pictures of your berry art!
Explorit’s coming events:
* Saturday: Explorit will be at the Children’s Summer Activities Faire from 9 a.m. to 1 p.m. at the Davis Farmers Market in Central Park, Fourth and C streets. Come visit our booth and find out about summer camp program offerings for 2012.
* Saturday: The Davis Astronomy Club will meet at 7 p.m. at Explorit at 3141 Fifth St. to discuss the rings of Saturn and telescope viewing of the night sky.
— Explorit Science Center is at 3141 Fifth St. and is open to the public the first full weekend of every month from 1 to 5 p.m. For more information, call (530) 756-0191 or visit http://www.explorit.org, or “like” us on Facebook at www.facebook.com/explorit.fb.