You know you’re a HS’er when you can chunk 5 lessons of science by looking in your pantry. Joel and Bethany both had lessons on solutions, compounds, mixtures, and chromatography. Of course they aren’t the same lesson, Joel’s are harder and go into a little more detail, but the basic premise is the same. So, we got the supplies and headed to the kitchen.

I amused Hannah for awhile with the gram scale, although she prefers it when I let her use beans instead of gram cubes (I guess because beans aren’t square and plastic.)

Of course every scientist needs safety goggles, even when you’re just mixing cornstarch and water.

Bethany did a solubility test on sugar, baking soda, and salt as the solutes. Then added solvents of soapy water, vinegar, alcohol and oil. Of course the baking soda/vinegar one went everywhere.

Salt did not dissolve in oil or alcohol, neither did sugar. Joel was mixing his own solution at this point: borax, glue and water. He made a new compound (slime) that was a mixture and a pure substance. It was also a homogeneous mixture (meaning that the mixture components are spread evenly in the mix.).

Grace and Hannah were making goop (cornstarch and water.) Its fun to play with, but hard to clean up!

You scrub and it turns hard and then you have to grab it quick before it slides right out of your hands. For chromatography we used coffee filters and black markers. They drew 2 lines on 2 different filters and then added alcohol to one and water to the other. The alcohol of course dissolves the pigments in the marker color and they spread according to color density. Usually cheaper black markers will display red, green, blue and yellow. These only did blue. We’ll have to gather 3 or 4 markers from different makers and try it again one day. Forensic scientist can use chromatography to study a paint sample from a car - finding out the model and the year the car was made.

We talked about ways to separate mixtures. You could distill, evaporate, use magnets, filters or chromatography. Bethany had to make 2 cups of sugar water and put one outside to evaporate and boil the other to see the difference. I’ll bet the bowl of water outside is gone by the end of the day. They also had to say whether something was a compound, mixture or element. Air – mixture, oxygen – element, water – compound.

Recipe for goop -
1 c cornstarch
½ c water
Mix until it looks smooth and wet. Now play! Roll it and it gets hard like a ball, stop and it’s a liquid. This never ceases to amaze the kids.

Recipe for slime -
1tsp borax
¼ c water
¼ c glue
1/4 c water
Mix glue and water until dissolved, then add borax to other ¼ c water and stir. Pour the glue solution into the borax solution and stir.

There’s a link on the blogroll for Wordle if you wanna play with it, it’s addictive!