23 February 2012

learning about: carbon dioxide!

after watching this video on carbon we discussed how the earth is like a recycling bin. the energy we get from the sun is constantly renewed, but water and other chemical elements (like carbon and nitrogen) on earth are used over and over again as living things take them in, use them, and them put them back into the environment. to demonstrate how the carbon cycle works we did an simple experiment with cabbage juice and some straws! 

for our experiment we poured a small amount of cooled cabbage juice into two cups. next, we took a straw and put it all the way against the bottom of one cup and blew through the straw repeatedly for a couple of minutes until we could see the cabbage juice turn pinker than the juice in the control cup. the carbon dioxide in our breath combined with the water in the cabbage juice to form carbonic acid, causing the pH of the solution to drop and the cabbage juice to turn pink. 

you can hardly notice the difference in this photo, but it was there!