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Law of Definite Proportions

Compounds contain the same elements in the same proportion by mass.

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Baking and the Law of Definite Proportions

Baking Grandma's Cake

In chemistry, the law of definite proportions dictates that any chemical compound always contains the same elements in the exact same proportions by mass. A good example is water because it will always have the same composition regardless of the amount you have. 

Credit: Deniss Mojado
Source: http://photography.mojado.com/archives/2004/04/27/chocolate_cake.php
License: CC BY-NC 3.0

Did Grandma know about the law of definite proportions? [Figure1]

Let’s say you want to bake your grandmother’s famous chocolate cake using her recipe. It calls for proportions such as 1 cup of flour to 1/2 cup of water, and 3 cups of sugar to 2 cups chopped chocolate chips.

Creative Applications

1. How does this recipe demonstrate the law of definite proportions?

2. If you wanted to make a bigger or smaller cake, how would you maintain the taste of the cake?

3. If you added only more flour or sugar, would you still have the same cake? Why or why not?

4. What would happen to the cake if you used the wrong proportions? 

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Image Attributions

  1. [1]^ Credit: Deniss Mojado; Source: http://photography.mojado.com/archives/2004/04/27/chocolate_cake.php; License: CC BY-NC 3.0

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