1. Chapter 10 The Mole

2. 10.1 Measuring Matter Dozen eggs Pair of gloves

3. The mole SI unit, measures the amount of substance 602,213,670,000,000,000,000,000 –A mole of pennies would be $6,022,136,700,000,000,000,000 –six sextillion, twenty-two quintillion, one hundred thirty-six quadrillion, seven hundred trillion dollars 6.02 x 10 23 particles of matter

4. 6.02 x 10 23 = Avogadro’s number –The number of representative particles in one mole of a pure substance –Representative particle = Formula unit (ionic compounds) Molecule (covalent compounds) Atom

5. Fe = 6.02 x 10 23 atoms H 2 O = 6.02 x 10 23 molecules CaCl 2 = 6.02 x 10 23 formula units

6. Conversion factor = –6.02 x 10 23 particles 1 mole How many atoms are in 2.00 mol of argon?

7. How many molecules are in 7.25 mol of carbon dioxide? Challenge: How many oxygen atoms are in 5.0 moles of oxygen molecules? (Oxygen is diatomic)

8. How many moles are in 1.62 x 10 23 atoms of argon? How many moles are in 4.35 x 10 24 molecules of dinitrogen triflouride?

9. 10.2 Mass and the Mole Molar mass = the mass in grams of one mole of a pure substance (atom, molecule, formula unit) –Equal to atomic mass (on periodic table) –Unit = g/mol

10. Mass of atoms is found on the periodic table –K = Mass of compounds must be calculated –H 2 0 –CO 2

11. Calculating molar mass What is the molar mass of barium acetate? What is the molar mass of ammonium sulfate?

12. How many moles are in 12.5 g of Carbon dioxide? How many moles are in 83.2 g of H 2 SO 4 ?

13. What is the mass in grams of 1.5 mol of sodium chloride? What is the mass in grams of 0.774 mol of oxygen?

14. Must ALWAYS go to moles first

15. Moles ParticlesVolumeMassParticlesVolumeMass

16. How many atoms are in a 44.3 g piece of iron?

17. What is the mass in grams of 2.3 x 10 22 formula units of sodium phosphate?

18. How many aluminum ions are present in 35.6 g AlCl 3 ? How many chlorine ions are present in 35.6 g AlCl 3 ?

19. 10.4 Empirical and Molecular Formulas Empirical formula – shows the smallest whole-number ration of atoms in a compound Molecular formula – gives the actual number of each kind of atom in a molecule C 6 H 12 O 6

20. Percent Composition The percent by mass of each element in a compound The percents of all the elements should add up to 100

21. Calculating % Composition 1.Find the total molar mass of each element in the compound. 2.Find the molar mass of the entire compound. 3.Divide the total molar mass of each element by the molar mass of the compound then multiply by 100 4.Check that all your percentages add up to 100

22. % composition of C 3 F 6 1.Total mass of C = total mass of F = 2.Mass of compound C 3 F 6 = 3.% of C = % of F = 4.Check your work!

23. What is the percent composition of phosphoric acid?

24. Empirical Formula The formula with the smallest whole number ratio of elements in a compound

25. Calculating Empirical Formulas 1.Change % to g (assume 100 g of compound so 30% = 30 g) 2.Convert each element from g to moles 3.Divide each mole amount by the smallest number from step 2 4.Change to a whole number = subscript in empirical formula

26. What is the empirical formula for a compound that is 48.64% Carbon, 8.16% Hydrogen, and 43.20% Oxygen?

27. What is the empirical formula of a compound that is 43.7% P and 56.3% O?

28. Molecular Formula To find the molecular formula you must know –Empirical formula –Molar mass of compound Can be the same as the empirical formula but often is not

29. Calculating Molecular Formula 1.Calculate the mass of the empirical formula 2.Divide molar mass of compound (will be given) by mass of empirical formula 3.Multiply each subscript in the empirical formula by the answer from step 2

30. A compound who’s empirical formula is NO 2 has a molar mass of 92 g/mol. What is the compound’s molecular formula?

31. An unknown compound contains 58.5% carbon, 9.8% hydrogen, and 31.4% oxygen. Its molar mass is 102 g/mol. What are its empirical and molecular formulas?