Introducing… Hellooo Students!!! Mr. MOLE

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 representative particles x is called AVOGADRO’S NUMBER. It is an equivalency—a conversion factor Just like…1 dozen = 12 pieces, 1 mole = 6.02 x pieces

Why 6.02 x ??? 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 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 representative particles. W W hat is a representative particle ? It is whatever you are counting: –Molecules –Formula units –Atoms –Ions

Our representative particle in this question is a molecule—it is what we are counting. We can use dimensional analysis: 1 mol CO 2 = 6.02 x molecules CO 2 A Typical Question: A Typical Question: How many molecules of CO 2 are there in 4.56 moles of CO 2 ? 4.56 mol CO 2 1 mol CO x molecules CO 2 (4.56) 6.02 x molecules CO 2 = 2.75 x molecules CO 2

Moving On… 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. 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 Using the periodic table, what is the molar mass of… Aluminum Lead g/mol g/mol Notice, we’re still talking about 1 mole. Each mole has the same number of particles (6.02 x ), just different masses! amugrams / mole g Al = 1 mol Al g Pb = 1 mol Pb

Finding the Molar Mass of a Compound H2OH2O 2 H = 2 x 1.01 = 2.02 g/mol 1 oxygen = 1 x = g/mol 2.02 g g = g/mol molar mass of water = g/mol It’s simple: Just add up its atomic masses. Example: What is the molar mass of water?

Calculate These Molar Masses: Mg 3 (PO 4 ) g/mol C 12 H 22 O g/mol

Molar mass 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? 1.Find the molar mass. (This will be the conversion factor.) Na: g/mol; Cl: g/mol; NaCl: = g/mol 2.Use dimensional analysis to solve g NaCl = 1 mol NaCl 1 mol NaCl 0.25 mol NaCl g NaCl =15 g NaCl

Another Practice Problem How many moles are in 25 g of NaCl? 1.Find the molar mass. ( This will be the conversion factor.) Na: g/mol; Cl: g/mol NaCl: = g/mol 2.Use dimensional analysis to solve. 1 mol NaCl = g NaCl g NaCl 25 g NaCl 1 mol NaCl =0.43 mol NaCl

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