Introducing… Mr. MOLE Hellooo Students!!!

Chemistry Joke Q: What did the proton say to the electron to make him happy? A: Something positive!

What is a MOLE? Abbreviated “mol” The amount of a substance that contains 6.02 x 1023 representative particles. 6.02 x 1023 is called AVOGADRO’S NUMBER. It is an equivalency—a conversion factor Just like…1 dozen = 12 pieces, 1 mole = 6.02 x 1023 pieces

Why 6.02 x 1023??? Because atoms are so small, Avogadro’s number has to be pretty big. How big? Scientists use this number because… It is the number of particles in 12 grams of carbon-12 602,000,000,000,000,000,000,000

If you had a mole of water molecules, how much water do you think this would be? 1 mole of water molecules (6.02 x 1023 molecules of water) is only about 18 mL of water !!

1 MOLE of Atoms

Using Moles in Chemistry Definition – the amount of a substance that contains 6.02 x 1023 representative particles. What is a representative particle? It is whatever you are counting: Molecules Formula units Atoms Ions

A Typical Question: How many molecules of CO2 are there in 4 A Typical Question: How many molecules of CO2 are there in 4.56 moles of CO2 ? Our representative particle in this question is a molecule—it is what we are counting. We can use dimensional analysis: 1 mol CO2 = 6.02 x 1023 molecules CO2 6.02 x 1023 molecules CO2 4.56 mol CO2 1 mol CO2 (4.56) 6.02 x 1023 molecules CO2= 2.75 x 1024 molecules CO2

Moving On… The MOLAR MASS!! Now that we can find how many representative particles are in a given number of moles, and… How many moles are represented by a given number of representative particles, We need to learn about the mass of a mole. The MOLAR MASS!!

Measuring the Mass of Moles Remember atomic mass? The amu (atomic mass unit) is one twelfth the mass of a carbon-12 atom. Since the mole is the number of atoms in 12 grams of carbon-12… The decimal number on the periodic table (average atomic mass) is ALSO the mass of 1 mole of those atoms in grams.

Finding the Molar Mass of Elements amu grams / mole Using the periodic table, what is the molar mass of… Aluminum Lead Notice, we’re still talking about 1 mole. Each mole has the same number of particles (6.02 x 1023), just different masses! 26.98 g/mol 26.98 g Al = 1 mol Al 207.20 g/mol 207.20 g Pb = 1 mol Pb

Finding the Molar Mass of a Compound It’s simple: Just add up its atomic masses. Example: What is the molar mass of water? H2O 2 H = 2 x 1.01 = 2.02 g/mol 1 oxygen = 1 x 16.00 = 16.00 g/mol 2.02 g + 16.00 g = 18.02 g/mol molar mass of water = 18.02 g/mol

Calculate These Molar Masses: Mg3(PO4)2 262.84 g/mol C12H22O11 342.34 g/mol

Molar mass is the generic term for the mass of one mole of any substance Also called: Gram Molecular Mass (molecules) Gram Formula Mass (ionic cmpds) Gram Atomic Mass (elements)

Practice Problem Using Molar Mass How many grams are in 0.25 mol of NaCl? Find the molar mass. (This will be the conversion factor.) Na: 23.00 g/mol; Cl: 35.45 g/mol; NaCl: 23.00 + 35.45 = 58.45 g/mol Use dimensional analysis to solve. 58.45 g NaCl = 1 mol NaCl 0.25 mol NaCl 58.45 g NaCl =15 g NaCl 1 mol NaCl

Another Practice Problem How many moles are in 25 g of NaCl? Find the molar mass. (This will be the conversion factor.) Na: 23.00 g/mol; Cl: 35.45 g/mol NaCl: 23.00 + 35.45 = 58.45 g/mol Use dimensional analysis to solve. 1 mol NaCl = 58.45 g NaCl 25 g NaCl 1 mol NaCl =0.43 mol NaCl 58.45 g NaCl

ChemistryJoke Q: What kind of music does a chemist listen to? A: Heavy Metal!