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news & tips

A collection of helpful articles on teachers and teaching

Soda Pop Science

In my chemistry class we have been measuring the density of lots of different liquids. By far the most interesting seems to be soda pop.  Regular Pepsi will float in a tank of water and diet Pepsi will sink. We have found a few diet sodas that sink and a couple of odd drinks that will float even though they have sugar.


The key is that sugar in regular pop has a greater mass than the artificial sweeteners they put in diet sodas. That makes the regular pop more dense.

 

There is a ton of science in there with the sweetness factor of sugar as compared to artificial sweeteners. But for today the interesting conversations in my room centered on how pop is made and what kids exist. Perhaps this interest stems from the fact that we Americans drink 49 gallons of pop per person each year and about 35 gallons of water. That is a lot of pop! We call it soda in some states and pop in others. Some places they call every soda by the trade name Coke even though it is something else.  Whatever you call it pop is about 94% carbonated water. Carbon dioxide is pumped through water to give it that sparkle and bite. They use CO2 because it is low cost, inert, non-toxic and it liquefies easily.

Sugar is the second main ingredient by mass and it can be 5% up to 18% of the total mass of the product. It is difficult to measure the CO2 in your lab but you could measure most of the sugar by heating the pop gently until it dries out. Most of the solid residue left after the water and CO2 evaporate will be sugar.
You can check out the history of soft drinks at: http://inventors.about.com/od/foodrelatedinventions/a/soft_drinks.htm

A great general background on all sodas is located at: http://www.madehow.com/Volume-2/Soft-Drink.html

Aside from the sugar and density tests there is a lot of chemistry in the flavorings. We in America tend to favor fruit and cola flavorings. Around the world there are some bizarre flavors. On the web we found a Pepsi that is cucumber flavored, soda that is salad flavored, one called Bon Bon which is grape juice with real grapes in the can, and my favorite “diet Water”. Smithsonian magazine online has a good article about carbonated milk and other odd sodas (http://blogs.smithsonianmag.com/food/2009/08/10/the-department-of-weird-soft-drinks-carbonated-milk/)

A good part of science is bold invention. It might be a good time to look in the fridge and see what flavors you would like to try in your pop?  Keep an inventors journal in case you come up with something really good. Anyone for watermelon cola?

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