Study Distraction: Do Calories Increase with Surface Area?

We all know what happens when we’re studying hard, we eat! Eating gives us strength to keep on going or it just distracts us from overusing our brains. Now after that fourth bag of candy, you start wondering…is there more sugar in a sugar cube or in a pile of sugar?

Actually maybe you’ll only have this question if you’re studying for the NYS Chemistry Regents.

Because, as you may know by now, there are five factors that affect the Rate of Reaction: Nature of the reactions, Surface area, Temperature, Concentration and Catalyst. The one we’re going to talk about today is…How the Surface Area Affects the Rate of Reaction:

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So we see that a pile of sugar has more surface area because there is a larger exposed area. Therefore, more surface area causes an increased rate of reaction. This means that regardless of what shape the sugar is in, you’ll be gaining the same amount of calories (check the accuracy of this with your nutritionist) but the way it gets broken down in your body can change! A decrease in surface area will cause a decrease in the rate of reaction.

Now let’s practice a Sample NYS Regents Question:

Fe(s) + 2HCl(aq) –> FeCl2(aq) + H2(g)

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The question is, what causes this reaction to occur more quickly when powdered iron is used instead of a single piece of iron of the same mass?

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Answer: The same way powdered sugar has more surface area, so does powdered iron. Because powder has more surface area than a single piece.

The difference is, I don’t think you’ll ever ever eat powdered iron while studying!

– Happy Studying!!

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Posted in Chemistry, Studying Tips

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