Avogadro’s Number
Now that you feel comfortable with mole to mole conversions, Avogadro’s number is just another step into the world of stoichiometry. Avogadro’s number is a gigantic number which represents the number of molecules per mole.
Avogadro's Number =
The number is so big that if I placed down bubblegum sticks around the world, I could go around the world a couple trillion times. That’s a lot of bubble gum! The scientists gave Avogadro’s number a funny definition of “The number of 12C atoms in exactly 12 grams of 12C. There is a reason why scientists have chosen the Carbon atom instead of hydrogen for example, but for now, let’s just get the general concept. By knowing the number of moles you have, you can also find the number of molecules by multiplying your moles by Avogadro’s number. Not bad, is it? It’s just another scary term for something really quite simple. Let's see if this makes any sense by doing a couple Problems.
| Problem 3.1 |
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| Problem: How many particles are in C6H6 (benzene) if I have 1.566 moles ?
Plan: Since we have the number of moles, all we need to do is multiply the number of moles by Avogadro's number. Answer:
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This problem above is as simple as they get. Sometimes all you need to do is multiply by Avogadro's number. In the next problem, one more step is added by asking for a specific number of atoms in a molecule.
| Problem 3.2 |
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| Problem: How many Hydrogen Atoms are in H2O(l) if I have 3.20 moles of H2O(l)?
Plan: First we will multiply the number of moles by Avogadro's number, then we will do a ratio of atoms H per atoms H2O. Since there are 2 H atoms per H2O, the ratio will be 2:1. Answer:
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That's about all we can talk about for now on Avogadro's number. It's a simple concept, but a powerful tool.
Understand Avogadro's Number? Let's check out Balancing Equations