Middle and High School … from a Montessori Point of View
While steam distillation is the recommended method for extracting oils from herbs, we’re trying a quick an dirty method of simply heating up the lavender leaves in water (up to 40 ºC) and seeing if any of the oils float to the top. If this does not work, we’ll still have produced some lavender scented water for our soapmaking.
The lavender leaves came from the large bushes out by the preschool that the outddoor group trimmed for Ms. Dicker.
We’ve looked at the simple acid/base reactions that produce the carbon dioxide bubbles in chocolate-chip cookies, but this video goes over a number of other relevant chemical concepts and the temperatures at which changes occur, including:
My chemistry students did a little experiment to investigate the effect of varying baking soda amounts on cookies. They did four batches of cookies based off of the recipe on the back of a bag of chocolate chips. The batches used:
The last batch used orange juice for its acidity. We hypothesized that more baking soda, and more acidity, would increase the size of the cookies, making them fluffier. The hypothesis was supported by our rather tasty evidence.
Although our focus was on the physical chemical reaction of the baking soda (sodium bicarbonate) and acid to produce the carbon dioxide bubbles that make the cookies rise, the making of the cookies also allowed us to talk a little about the food science behind the role of the flour. Specifically, we discussed the long chain gluten proteins that stretch out and trap the bubbles. We’ll talk a bit more about this next time when we make bread.
Scientific American has an article on “The Scientific Secret of Fluffy Pancakes” that nicely covers the chemistry of gluten. The article includes a recipe, but I tend to prefer buttermilk pancakes (Cook’s Illustrated has a great buttermilk pancake recipe that I find tastes even better if you leave out the sugar).
My wife has been experimenting with gluten-free pancakes and I’ve discovered that I like hers even better because of all the ground nuts it includes. However, in the gluten-free recipes, crucially, Xanthan gum is used to replace the gluten in capturing the carbon dioxide bubbles created by the baking powder reacting with the acid in the recipe. While the gluten is sensitive to how much the batter is mixed (stretching out the proteins), the quantity of Xanthan gum is more important in the gluten-free recipes.
↬ Maggie Eisenberger.
This nice little video combines a bit of physics, chemistry, and biology as it discusses how bubbles form in champagne: the gas is carbon dioxide; carbon dioxide forms from the fermentation of sugars by yeast — it’s a byproduct of the reaction that produces alcohol; the bubbles form at tiny flaws or bubbles in the glass (so you can put in tiny flaws to control where the bubbles form); the bubbles rise because the gas is less dense than the liquid around it; and the bubbles expand as they rise because the pressure of the liquid becomes less and less the closer to the surface you are.