Lab Set Up – Solubility Factors
There are (as far as I know) only two ways to teach the factors that affect solubility. You either tell them, and they remember it, or you have them figure it out, and have them tell you.
I’m pretty sure you can guess which tactic I use.
I’ve done the set up a few different ways. I initially did this lab as a stations lab simply because I didn’t have enough stirring rods for each group of students to have their own, but nowadays I’m lucky enough that this isn’t a problem.
So I give the kids graduated cylinders, 2 beakers, a stirring rod, a sugar cube and 5 pre-measured samples of sugar, weighing in at 2.5 grams. There aren’t enough balances for me to give one to every pair of students (I’d need 13 of them). This is especially hard when the other science teachers in the department are looking for the balances. It’s just easier for me to pre-measure the samples. The kids measure out the water in the graduated cylinders. We have the proper materials for this, and to be honest, my kids could use the practice.
Solubility Factors
The first round is surface area – I try to get the kids to get that sugar cube out of the way first. For whatever reason, my students are completely fascinated with them. They add equal amounts of water to each beaker, and then drop in the sugar cube and a sample of granulated sugar into each one. They then determine which sample is dissolving better. If you wanted to get real technical, they could get a stopwatch and time it.
Up next is temperature – The kids take a sample of warm water from me. I usually heat it up in my electrical kettle and turn it off before it starts boiling. The water just needs to be 20 to 30 degrees warmer than the tap water to see the difference. Again, the kids add equal amounts of water to each beaker and dump a sample of sugar into each.
Last is agitation – We’re back to tap water (whatever temperature that is), the kids dump in the sugar, but only stir one of the samples.
I don’t teach the factors that affect solubility
My favorite part of this lab is having a kid “be the teacher.” This kid will get up in front of the room, makes sure everyone calls them Ms. or Mr. Whomever and teaches the factors that affect solubility. I like to pick a kid that needs a little extra love or attention. I’ve also been known to pick a trouble maker. It gets them to realize what it feels like to be a teacher. One of the reasons this lab is so successful is because it’s pretty intuitive. The kids kind of know what the answers are supposed to be. The lab is really just to get them to solidify their preconceptions. It can also correct a few kids who may have something backwards.
Aside from supervising the lab and making sure nobody is getting hurt or doing the wrong thing, this is a pretty easy day for me. It’s a green chemistry lab. So I don’t have to worry much about the chemicals (just contamination from the equipment, really). You can read more about my green chemistry labs here.
You can get the specific lab form I use here. I hope this gives you an idea on how you can morph your factors that affect solubility lab or activity so that it’s easier on you! You can also read more about how my students write lab reports here, or skip the reading and just get a copy of the free lab rubric I use instead.
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