Chemistry sometimes gets a bad rap. Chemicals can be poisonous, make us sick, or harm the earth. The truth is we are all made up of many different kinds of chemicals. The food we eat is made of chemicals. We cook with chemicals. Our medicines are chemicals. In this activity students mix two household chemicals.
But before we start measuring and mixing chemicals we need to think safety. While I know you don’t wear safety goggles while you’re baking, or dressing your salad, it is very important to instill a life-long habit of “thinking safety” while doing activities where there is any concern of possible eye injury.
Safety goggles and glasses are available locally at Lowes or Home Depot, but they are adult sizes. Here’s a link for child-sized ones. Note their proviso (below, in red) about goggles ($5.95) vs. glasses ($2.95).
***Only Safety Goggles give the impact and splash protection required for working with chemicals. Safety Glasses give good impact protection.***
In our first chemistry lesson, second graders mixed baking soda and vinegar. Bubbles fizzed and popped. And yes, it IS possible to catch all those bubbles if you do the mixing in a Ziploc bag! Here is a link to my lesson plan: 2nd – Chemistry, baking soda + vinegar. Please do wear your safety goggles.
Another, different way to do this experiment is to put the vinegar into a clean 20 oz. soda bottle. Put the baking soda into a balloon. (Double the amounts of baking soda and vinegar.) Without spilling the baking soda into the bottle, stretch the mouth of the balloon over the mouth of the bottle. Now spill the baking soda into the bottle.
Students will usually describe the Ziploc bag or balloon as filling up with air. The bubbles that form as the two chemicals react are NOT air. It is the gas carbon dioxide, the same gas we animals breathe out. The same gas that plants “inhale.” Enough gas is generated to fill the Ziploc bag, or to inflate the balloon.