17 Sep

I Can Buy CaCl2 in the Paint Department? Really?

Over the years I’ve learned I do not have to purchase everything I need from a chemical supplier. A classic lab every science teacher knows and loves is Chemistry in a Bag. In its simplest form, a spoonful of calcium chloride and sodium bicarbonate are placed in opposite corners inside of a ziplock baggie. Then a small ketchup cup filled with about 1 cm of any pH indicator is gently slid into the baggie so it does not spill, the excess air is squeezed out and the bag is sealed. The student then topples over the ketchup cup and gently massages both the sodium bicarbonate and calcium chloride with the indicator and a chemical change occurs. This is a great lab where students have the opportunity to observe a color change, bubbles, hot and cold spots, and the bag inflate with a new gas produced as a result of the chemical change. There are so many variations of this lab on the internet because it can be easily modified for any grade level and tweeked to illustrate everything from conservation of mass, to gas stoichiometry and limiting reactants. It is also a 10 on the clean-up scale because the baggie just goes into the trash. Here’s the kicker- where do you purchase your calcium chloride? Calcium chloride is readily available in any home improvement or big box store as the closet dehumidifier, DampRid. You can purchase a huge tub of it in the paint department or ironing board aisle for a quarter of the cost you would pay elsewhere. I also purchase red cabbage juice extract you mix up like a powdered drink from Educational Innovations. Keeping both of these on your shelves and learning how you can expand this classic lab to meet a variety of curriculum needs will give you a big bang for your buck. Do you have your own version of Chemistry in a Bag you would like to share or do you know of other chemicals you can purchase this easily? Share with us!

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