2. INTRODUCING THE MOLE CHEMICAL QUANTITY

3. WHAT DO WE MEAN BY MOLE ? The animal with the weird nose? The popular sauce in Mexican cuisine? A dark “spot” on a person’s face or body?

4. THE MOLE WE ARE TALKING ABOUT The mole is a counting number (like a dozen)used in chemistry to express amounts of a chemical substance It is also referred to as Avogadro’s number 6.022 X 10 23 or 602200000000000000000000 A VERY large amount.

5.  1 mole of hockey pucks would equal the mass of the moon!  1 mole of pennies would cover the Earth 1/4 mile deep!  1 mole of basketballs would fill a bag the size of the earth!

6. EXAMPLES  A dozen eggs is how many eggs? 12  A dozen boron atoms is how many boron atoms? 12  A mole of eggs would be how many eggs? 6.022 X 10 23  A mole of boron atoms would be how many boron atoms? 6.022 X 10 23

7. FINDING THE MASS OF ONE MOLE OF AN ATOM OR MOLECULE. To find out how much one mole weighs for an atom, you can go to the periodic table and find that element’s ____________________________. This is also referred to as an element’s _________________________. Atomic mass Molar mass

8. PRACTICE What is the mass of one mole of copper? Answer: 63.55 g What is the molar mass of lead? Answer: 207.2 g

9. WHAT ABOUT COMPOUNDS? Steps to finding the molar mass of a compound Step 1: List the elements in the compound and the number of atoms you have for each element. Step 2: Write the molar mass of each element and multiply it by the number of atoms. Step 3: Add the masses for each element to get the molar mass (Make sure you are following rules for sig figs)

10. PRACTICE Water Formula: H 2 O H: (2)(1.008)+ O:(1)(16.00) = 18.02 g/mol Sodium Chloride Formula: NaCl Na: (1)(22.99)+ Cl:(1)(35.45) = 58.44 g/mol

11. MORE PRACTICE sodium bicarbonate Formula: NaHCO 3 Na: (1)(22.99)+ H: (1)(1.008)+ C (1)(12.01) + O: (3)(16.00) = 84.01 g/mol sucrose C 12 H 22 O 11 C: (12)(12.01)+ H: (22)(1.008)+ O: (11)(16.00) =342.30 g/mol

12. MOLAR CONVERSIONS 1.Write down your given and what you are trying to find 2.Cross out to get what you want 3.Use mole island (p.15 CRM) 4.Significant figures is determined by the given 5.Always include the compound and unit (remember sig figs)

13. EXAMPLE How many moles of boron are in 25 g of boron? 25 g of B 10.81 g of B = 2.3 mol of B 1 mol of B

14. PRACTICE How many moles of NaCl are in 100 g of NaCl?

15. MORE CONVERSIONS We now can go between mass (grams) and moles How do we go between moles and number of particles or vice versa? Remember that Avogadro’s number is the number of particles in a mole Therefore that will be our conversion factor 1 mol = 6.02 X 10 23 atoms, molecules, or representative particles

16. CONVERTING NUMBER OF ATOMS TO MOLES Magnesium is a light metal used in the manufacture of aircrafts, automobile wheels, tools, and garden furniture. How many moles of magnesium is 1.25 X 10 23 atoms of magnesium? KNOWNS: # of atoms = 1.25 X 10 23 atoms Mg UNKNOWN: Moles of Mg = ? 1.25 X 10 23 atoms Mg 2.08 X 10 -1 = 0.208 mol Mg 1 mol Mg 6.02 X 10 23 atoms Mg

17. NOW YOU TRY How many moles is 2.80 x 10 24 atoms of silicon?

18. YOUR TURN How many molecules are in 1.14 mol SO 3 ? How many moles are in 4.65 X 10 24 molecules of NO 2 ?

19. CONVERTING MOLES TO NUMBER OF ATOMS Propane is a gas used for cooking and heating. How many atoms are in 2.12 mol of propane (C 3 H 8 )? KNOWNS: # moles = 2.12 mol C 3 H 8 1 mol C 3 H 8 = 6.02 X 10 23 molecules C 3 H 8 1 molecule C 3 H 8 = 11 atoms (3 carbon atoms and 8 hydrogen atoms) UNKNOWNS: Number of atoms = ? 2.12 mol C 3 H 8 6.02 X 10 23 molecules C 3 H 8 11 atoms 1 mol C 3 H 8 1 molecule C 3 H 8 = 1.4039 X 10 25 = 1.40 X 10 25 atoms

20. MOLE-VOLUME RELATIONSHIP Volume of a Gas Gases are difficult to weigh (mass) The volume is effected by temperature and pressure Gases must be compared at the same temperature and pressure when finding the amount of moles of gas we have

21. STP Standard Temperature and Pressure 0 0 and 1 atmosphere (atm) of pressure At STP, 1 mole of any gas occupies 22.4 L This is referred to as molar volume 1 mole = 22.4L of gas at STP

22. EXAMPLES What is the volume of 4.59 mole of CO 2 gas at STP? 4.59 mol of CO 2 22.4 L CO 2 = 103 L of CO 2 1 mol CO 2

23. MORE PRACTICE How many moles is 5.67 L of O 2 at STP?

24. What is the volume of 8.8 mol of CH 4 gas at STP?