The Mole

What is a mole? A. a blind furry animal B. a brown mark on your body C. an important Chemistry concept D. All of these

As you may have guessed… D is the correct answer! Although a mole might be semi-cute and fuzzy, we are obviously focusing on the Chemistry concept.

A mole is a counting unit. Just like… 12 eggs equals a dozen eggs 144 pencils equals one gross of pencils 60 seconds equals one minute 500 sheets of paper equals one ream

One mole equals 6.02 x 1023 particles So one mole of eggs would be 6.02 x 1023 eggs One mole of pencils would be 6.02 x 1023 pencils And so on…

Where did the mole come from? The unit, called the mole (or mol), is defined as the number of atoms in exactly 12 g of the carbon-12 isotope. The number of particles in one mole, 6.02 x 1023, is known as Avogadro’s constant or number. This number was named after a famous dead guy, Amadeo Avogadro (1776-1856), whose ideas were crucial to the early development in Chemistry.

6.02 x 1023 is a very large number! If we did not use scientific notation to write out 6.02 x 1023, we would write 6022 with 20 zeros after it. 602,200,000,000,000,000,000,000 Wowsa!

Imagine that we had a mole of gumballs If all 6 billion people on Earth were to do nothing but count the gumballs in one mole at the rate of one gumball per second, it would take over 3 million years to count all the gumballs!

What is all of this used for? Avogadro’s constant can be used to convert an amount of moles into the equivalent number of particles. Important notice! Avogadro’s number can describe: particles atoms molecules formula units

Welcome to the city of Moleville (mol) Avogadro’s Number Molar mass Atoms, molecules, particles, formula units Mass (g) Welcome to the city of Moleville (mol) Molar volume of a gas Molar volume (L)

How many atoms are in 3.5 moles of copper? 1 mole of copper contains 6.02 x 1023 atoms 3.5 moles Cu x 6.02 x 1023 atoms = 1 mole Cu 2.11 x 1024 atoms in 3.5 moles of Cu

How many atoms are in 7.5 mol of Argon? Before you start throwing down random numbers, think about the problem. Should the final answer be bigger or smaller than 6.02 x 1023? Since 1 mole is 6.02 x 1023 atoms, 7.5 moles has to be a larger number of atoms. Thinking through the problem before you begin will help you to know if you correctly solved the problem. Solve it!

How many atoms are in 7.5 mol of Argon? 7.5 mol Ar x 6.02 x 1023 atoms = 1 mol Ar

Try the following problems 1. How many atoms are present in 3.7 mol of sodium? 2. How many atoms are present in 1.55 mol of arsenic? 3. How many moles of Xenon is 5.66 x 1026 atoms?

And the answers are… 2.2 x 1024 Na atoms 9.33 x 1025 As atoms 3) 940.0 mol Xe

A few pointers: THINK about the problem before, during, and after your work. Does the answer make sense? Follow the set-up by showing your work. We are not being mean, instead, this is the best way to ALWAYS get the correct answer.

Mole Jokes Who is Avogadro’s favorite actor? Mol Gibson! Where did Avogadro go on Saturday? the shopping mole What did Avogadro have on his pancakes? molasses You are probably thinking these jokes are remolting…

You want one more??? Why did Avogadro look forward to the year 2000? It was the start of the new molennium!!

Changing from mole to mass We now know how many particles are in a mole, BUT we also need to know how much a mole weighs. Thus, we bring up the term, MOLAR MASS.

Molar Mass The mass of 1 mole (in grams) Equal to the numerical value of the average atomic mass (remember how we calculated using the Periodic Table?) 1 mole of C atoms = 12.0 g 1 mole of Mg atoms = 24.3 g 1 mole of Cu atoms = 63.5 g

Other Names Related to Molar Mass Molecular Mass/ Molecular Weight: If you have a single molecule, mass is measured in amu’s instead of grams. But, the molecular mass/ weight is the same numerical value at 1 mole of molecules. Only the units are different. (This is the beauty of Avogadro’s number! Formula mass/ Formula weight: same goes for compounds. But, again, the numerical is the same. Only the units are different. ALL OF THESE TERMS MEAN THE SAME NUMBER…JUST DIFFERENT UNITS.

Time-out and Check! Find the molar mass (usually we round to the tenths place) A. 1 mole of Br atoms = 79.9 g/ mole B. 1 mole of Sn atoms = 118.7 g/ mole

Molar Mass of Molecules & Compounds Mass in grams of 1 mole equal numerically to the sum of the atomic masses 1 mole CaCl2 = 111.1 g/mol 1 mol Ca X 40.1 g/mol = 40.1 g + 2 moles Cl X 35.5 g/mol = 71.0 g 1 mol CaCl2 = 111.1 g

Try it! Molar Mass of K2O = ? Grams/ mole Molar Mass of antacid Al(OH)3 = ? Grams/ mole

Now try this doozy… Prozac, C17H18F3NO, is a widely used antidepressent that inhibits the uptake of serotonin by the brain. Find its molar mass.

Converting Moles to Grams Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al  ? g Al

Practice The artificial sweetener, aspartame, has a chemical formula C14H18N2O9 is used to sweeten diet foods, coffee, and soft drinks. How many moles of aspartame are present in 225 g of aspartame?