1 The Mole 6.02 X 10 23

2 The Mole Count w/ it kinda like a dozen, except instead of 12, it means 602,000,000,000,000,000,000, X (in scientific notation) Amedeo Avogadro (1776 – 1856)This number is named in honor of Amedeo Avogadro (1776 – 1856), who made a pretty sick hypothesis back in the day that turned out to be true... “If equivalent quantities of different gases are compared, the amount of molecules present will be the same due to constant temperature and volume.”

3 Just How Big is a Mole? 6.02 x cans of pop would form a 200mile deep layer over the Earth. Not even Mr. Stephan could drink that much Mt. Dew. If you took a mole of moles and lined them all up into a mega molestick, you could poke nearby stars with it. That star is over 4 light years away.

4 Everybody Has Avogadro’s Number! But Where Did it Come From? Scientists didn't randomly pick 6.02x10 23 to be the mole. Remember that Robert Millikan guy who did the oil drop experiment in 1909? That experiment helped scientists figure out how big a mole should be. Yeah, this guy. I bet you forgot all about him even though you remember people like Dalton and Bohr... kind of a big deal. Show some respect.

5 The Mole 1 dozen cookies = 12 cookies 1 mole of cookies = 6.02 X cookies 1 dozen cars = 12 cars 1 mole of cars = 6.02 X cars 1 dozen Al atoms = 12 Al atoms 1 mole of Al atoms = 6.02 X atoms Note that the NUMBER is always the same, but the MASS is very different! Oh, and the unit for Moles is “Mol.”

6 = 6.02 x C atoms = 6.02 x H 2 O molecules = 6.02 x Na + ions AND 6.02 x Cl - ions A Mole of Particles A Mole of Particles Contains 6.02 x particles 1 mole C 1 mole H 2 O 1 mole NaCl

x particles 1 mole or 1 mole 6.02 x particles Note that a particle could be an atom OR a molecule! Avogadro’s Number as Conversion Factor

8 1. Number of atoms in mole of Al a) 500 Al atoms b) 6.02 x Al atoms c) 3.01 x Al atoms 2.Number of moles of S in 1.8 x S atoms a) 1.0 mole S atoms b) 3.0 mole S atoms c) 1.1 x mole S atoms Learning Check

9 #1. Atomic # (how many protons) #2. Atomic Symbol #3. Atomic mass (mass of one atom) #4. Molar mass (one mole of that element) Periodic Table

10 Measuring mass Atomic mass: The mass of one atom of that element. The atomic mass is measured in “amu” – atomic mass units. Molar Mass: The mass of one mole of that element. Molar mass is measured in “g/mol.” You can also figure out the molar mass of molecules by adding up the molar masses of all the elements that make it up. IMPORTANT: Both of these values are the SAME NUMBER, just different units...

11 Why use Molar Mass? 1 Mole of a substance is a very handy amount to work with. Check out these moles of different elements:

12 Why use Molar Mass? You can have 1 mole of ionic compounds too ( in case you forgot, Ionic = Cation + Anion bonding together ):

13 Molar Mass of Molecules Molar Mass is a measured number, so significant figure rules are still a thing we're doing.

14 Using Molar Mass in Dimensional Analysis Use Molar Mass as a conversion factor; however, as a measured number it WILL affect significant figures. Ex: 1 mole H2O grams

15 A.Molar Mass of K 2 O = ? 2 Potassiums → ________g/mol 1 Oxygen → ________g/mol Total = ____________g/mol Learning Check!

16 A.The Molar Mass of (NH 4 ) 3 P is 85.12g/mol 1. What is the name of this substance? 2. What is the mass of 3.50 moles of this substance? 3.50 mole (NH 4 ) 3 P x grams = _______ grams 1 1 mole Learning Check!

17 Aluminum is often used as a key component of light-weight bicycle frames. Let's say 6.75 moles of Al are needed to make one bike frame. How many grams of Al are needed? Converting Moles and Grams

18 The artificial sweetener aspartame (Nutra-Sweet) formula C 14 H 18 N 2 O 5 is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame? Learning Check!

19 Using mass to determine how many atoms/molecules are present... You can use a combination of two different conversion factors to convert “mass” to “number of atoms/molecules” 6.02 x particles & 1 mole 1 mole X grams

20 Atoms/Molecules and Grams How many atoms of Cu are present in 35.4 g of Cu? 35.4 g Cu 1 mol Cu 6.02 X atoms Cu 63.5 g Cu 1 mol Cu = 3.4 X atoms Cu

21 Warning: What I am going to teach you next ONLY WORKS WITH GASES. Don't try to do this with solids or liquids! Make sure you know what 11 elements I'm talkin' about when I say “GASES”. Mark them on your periodic table so you don't forget what they are.

22 Volume of a gas: Remember the other day I was telling you about how Mr. Avogadro had this sick hypothesis about measuring quantities of gas? Here's another conversion factor you can use thanks to him: Assuming STP... 1 Mole of a gas = 22.4L

23 Memorize these: All have 3 significant figures!

24 Warning: The 22.4L per mole conversion factor ONLY WORKS WITH GASES. Don't try to do this with solids or liquids! Hydrogen Krypton Helium Neon Nitrogen Argon Oxygen Xenon Fluorine Radon Chlorine

25 Warning: The 22.4L per mole conversion factor ONLY WORKS AT STP CONDITIONS. It is possible to do these kind of problems if its not STP, but its way more complicated – we're not learning that yet. STP : Standard Temperate and Pressure means 1 atm at 0°C (273K).

26 Practice Problem #1 At 273K and 1atm, what is the amount of space occupied by 7.95 x Neon atoms? (hint: use two conversion factors)

27 Practice Problem #2 Under standard conditions, a balloon is filled with 1.18 grams of Helium. How large will the balloon become? (hint: use two conversion factors)

28 Practice Problem #3 There is a room at STP that contains 51.0L of Oxygen. How many oxygen atoms are in that room? (hint: Oxygen is a diatomic gas)

29 One more thing... If I know the MASS of one mole of a gas, as well the VOLUME of one mole of a gas, what else do you think I can figure out? Mass x Moles = Mass Moles Volume Volume