The electrons in a molecule of water are arranged so that each water molecule is extremely attracted to the one next to it. Because of this they naturally arrange themselves at the atomic level in ways that have big consequences in the world around us. When water freezes, the molecules arrange in a way that creates a lattice that causes ice to float in liquid water. Why is that so important? Because ice floats, a pond or lake will freeze at the top, but below the entire aquatic ecosystem is able to survive.
This is an amazing phenomenon of water. Many other substances adopt their own unique properties due to arrangement of electrons. The propane gas that we use to fuel a gas grill is a gas at room temperature because the molecules are weakly attracted to each other. Consequently, the space between them results in a gaseous state. Another important gas is oxygen. We need oxygen to live out our lives. Close your eyes and take a deep breath.
As you do that, the molecules are whizzing through your nose, into your lungs where about 0. Those molecules are responsible for helping each cell in your body produce energy so that your eyes can see the words on this page and your brain can think about what they mean, all while keeping your heart beating. So, in other words, one mole of atoms of carbon is 6. Altogether, that many atoms weigh 12 grams. A mole of pumpkin spice lattes, to use a seasonally appropriate reference, is 6.
That many lattes weighs a lot more than 12 grams, though. More on that later. Yes, the number is the reason for the choice of date. Real purists celebrate between AM and PM. It can be tough to wrap your mind around a number that big. My high school chemistry textbook put it this way: If you had one mole of marbles— 6. The name specifically honors nineteenth-century Italian chemist Amedeo Avogadro , because his work with gases was among the first to help scientists make sense of that relationship.
I don't want the mass density. I want the number density how many grains per unit of volume. Just a little unit conversion gives:. Now we are getting somewhere. I know the number-density, so I can calculate the molar volume for grains of salt. That is one big pile of salt. If you were to put it in a cube, it would be 44 km tall 27 miles - yeah, that's high.
Here, I made some images with Google Earth. For some reason, I put my giant cube of salt grains in Maimi, Fl. Here is what that would look like:. What if I were in Tampa, Florida? I could still see it. This is some random location near Tampa looking towards Miami. What if you wanted to spread it out. You know, so you could see the top? In fact, that is enough salt to evenly spread over the surface of the Earth and be 17 cm thick. Oh, I know - I could get smaller stuff.
Maybe I could see something about 10 times smaller than salt. That wouldn't help. Suppose that increases the number density by that is 10 3. That would still make a cube that was 4 km on a side.
Avogadro's number is gianomrous. It is so big, you can't see it. That number of particles is Avogadro's Number , which is roughly 6. A mole of carbon atoms is 6. A mole of chemistry teachers is 6. It's a lot easier to write the word 'mole' than to write '6.
Basically, that's why this particular unit was invented. Why don't we simply stick with units like grams and nanograms and kilograms, etc. It's simply a convenient unit to use when performing calculations. You may not find it too convenient when you are first learning how to use it, but once you become familiar with it, a mole will be as normal a unit as, say, a dozen or a byte.
One of the most common chemistry calculations is converting moles of a substance into grams. When you balance equations, you'll use the mole ratio between reactants and reagents.
To do this conversion, all you need is a periodic table or another list of atomic masses. Example: How many grams of carbon dioxide is 0.
Look up the atomic masses of carbon and oxygen. This is the number of grams per one mole of atoms. Carbon C has Oxygen O has
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