We’re in for some messy fun as we look for similarities between “lava” and biscuits in Science Friday’s 6th installment.
This science experiment with my preschooler was pretty involved (read: lots of dirty dishes) but the rewards were great because he got really excited. We made a play dough volcano and caused an eruption as well as observed what happened when we left baking powder out of a biscuit recipe.
Play dough- homemade or otherwise
Liquid dish soap
We made purple play dough and pressed it around an inverted funnel which we placed over a large pile of baking soda in a plastic container. (Seal the edges down at the base, or use a small water bottle with baking soda inside it instead of a funnel.)
Mix up 1/4 cup vinegar with 1/2 cup water, desired dye, and a couple squirts of dish soap. Pour this mixture into the volcano and, voila! You and I have seen this before, but to a first-timer, it is SUPER fun and every kid should have a chance to do this classic activity.
What makes the foam? It is the result of two chemical reactions. The acetic acid in the vinegar reacts with the sodium bicarbonate to form carbonic acid. This quickly decomposes into carbon dioxide and water. When the CO2 gas escapes in the bubbles, the remaining solution is sodium acetate in water. You can see the chemical formula here, but your four-year-old won’t care.
We talked a bit about how sometimes two things can combine to make bubbles and, without getting too technical, set out to see how this happens in our food. I explained that baking powder is a lot like the baking soda we just used; when it’s in food it can make bubbles that make the food rise.
Preheat oven to 425F (220C). Using two mixing bowls, put 1/2 cup of flour and 1/8 tsp salt in each. In one bowl, add 1/2 Tbsp baking powder. Mix each bowl. Add 1 1/2 Tbsp shortening to each and incorporate fully. Add just enough milk to each to form a soft dough (a Tbsp or two). Roll out and cut- makes about 2 of each.
Place them on a baking sheet and pop in the oven for 10-15 minutes, until lightly golden.