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Surface Area

We're Lara and Anushua and we're nuts about baking! So, we headed to the Baking Lab at the Mill City Museum in Minneapolis where we made sugar cookies. While the cookies were in the oven, we sat in on a demonstration about the explosive nature of flour dust. Turns out that flour mixed in the air was more explosive than the same amount of flour in a cup. Back in the lab, we noticed that the size of our cookies had an effect on the amount of sugar we used. We found this very intriguing and decided to head to the Science Museum of Minnesota to figure out: How does surface area affect how things react?

What did we do?
We ran into Mahmoud at the Experiment Gallery at the Science Museum of Minnesota. He had us calculate the surface area of one big block (54 units) and then the total surface area of all the little blocks that made up the one big block (162 units). From there Mahmoud sent us to the museum's Big Backyard to perform a soda explosion experiment. We tried the experiment with rocks, pebbles and sand to see which would cause the biggest soda geyser. We also spent some time at the Science House learning how cookies, Soda Geysers, and Solar Panels are all connected. Are you curious? Read on!

What did we find out?
Breaking something (like a piece of candy) into really small pieces increases its surface area. That's why we used more sugar when making the smaller cookies than the one big one, why 25 grams of sand caused a bigger soda explosion than 25 grams of rocks and why a carpet of nanowires on a solar cell can absorb more sunlight than a thin, flat film!

What can you do?
  • Grab a partner for a dissolving contest! Each of you should put a piece of hard candy (like a Life Saver) in your mouth at the same time. One of you should crush the candy with your teeth. The other should let the candy dissolve on its own. Which dissolves faster? Why?
  • Make a batch of sugar cookie dough and divide it in half. Take one half and roll it into 1 giant ball. Use 1 Tablespoon of sugar and try to completely cover the cookie. Roll the other half into as many small cookies as possible. Use 1 Tablespoon of sugar and try to completely cover as many cookies as you can. Did you ever run out of sugar? Why? Will the large and small cookies take the same amount of time to bake?
  • Grab 2 cups. Take 1 tablespoon of baking soda and add a little bit of water so that you can roll it into a ball and place it in the first cup. In the second cup, put 1 tablespoon of regular baking soda. Add 1/2 cup of vinegar to both cups at the same time. Which one reacts faster?
  • Lend a hand in the kitchen. The next time your family is melting butter, tell them what you know about surface area and help them chop up the chunk of butter so it melts even faster!
more resources
Factors affecting reaction rate

whiz quiz

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