If you're looking to have some Valentine's fun with your children, and have them learn something at the same time, Lisa Bergantz came on Good Things Utah with some of her "Smmart Ideas".
She says the vocabulary for these experiments is carbon dioxide.Pumping Heart Model
The heart has long been the symbol of poetic love and a widely used symbol on Valentine's Day.
Have your child breathe in and explain that their lungs are being filled with Oxygen that our bodies use. Our blood picks up the oxygen from our lungs. Our blood carries the oxygen all through our bodies and picks up the CO2 that we won't use. Then it's released from our blood into our lungs for us to breathe out.
Our heart is a huge muscle that pumps our blood all through our bodies. This model shows how the heart muscle can pump blood.
You can make this model of a heart with your child to demonstrate how blood is pumped around the body. Why does our blood only pump in one direction? (answer: the valves close off and do not allow the blood back into the chamber it just came from.)
You can see how to make a model heart here:http://www.smm.org/heart/lessons/lesson5a.htm
Good 'ol baking soda and vinegar! These two substances react to form Carbon Dioxide. A solid (Baking Soda, or Sodium Bicarbonate) and a liquid (Vinegar, or Acetic Acid) react to form a gas!
Fill a tall, clear glass half full of water. Let your child drop in 2 or 3 little candy valentine hearts (conversation hearts). Observe the hearts. Now stir in a Tb of Baking Soda (sodium bicarbonate). Observe the hearts. Do you see any bubbles forming along the edges? Pour in a little Vinegar (acetic acid). Observe the hearts. Do you see any bubbles forming along the edges?
Wait for a moment and you will see the bubbles form along the edges of the hearts...so many bubbles that they buoy up the heart so that it rises to the top of the water. The hearts will rise and fall. Why do the hearts fall? Why do they rise again?
Remind your child that this is the same gas that we breathe out of our bodies and that plants use.Love Potion
Another round of Baking Soda and Vinegar to create a Carbon Dioxide explosion! You've probably all done this reaction at home, but put this Valentine's Day twist on it for a lot of chemistry fun!
Pour a Tb of Baking Soda (Love Powder) into a tall, clear glass. We used a vinaigrette cruet because it looked more like a potion bottle. Drop in 2 drops of red food coloring. Have your child drop in one or two valentine candies (just for fun- they don't effect the reaction).
Now pour a tiny bit of vinegar (Valentine's Day juice) into the bottle and swirl it all around quickly. Watch the liquid turn red and dissolve the solid baking soda. It will bubble slightly. Now pour a bit more vinegar into the bottle and observe the power of the Love Potion! Be sure to do this fun little experiment over the sink:)
You can get more of Lisa's ideas at: http://www.smmartideas.blogspot.com