1. Unit 6 Mole Calculations

2. The Mole Mole – measurement of the ______________ of a substance.
We know the amount of different substances in one mole of that substance.

3. Atomic Mass Unit Mass of 1 mole of compound
Found by adding the atomic weights of each atom of each element that makes up a compound.
H2O
There are 2 atoms of hydrogen and 1 atom of oxygen.

4. AMU H = 2 x 1.01 = 2.02 O = 1 x 16 = 16 _____ 18.02 = amu
1 mole of any substance = the amu of that substance

5. AMU
______________= the sum of the molar masses of atoms of the elements in the formula
Calculated the same way

6. The Mole One mole of any substance has Avogadro’s number.
6.022 x 1023 atoms, molecules, ions

7. The Mole
For gases only – 1 mole of a gas occupies L

8. Converting Between Units
amu  1 mole  x 1023 atoms, mlc, ions 
22.4 L
Gas

9. Conversions
Change 5.0 grams of sodium chloride to moles of sodium chloride.

10. conversions
Change 0.45 moles of barium chlorate to grams of barium chlorate.

11. conversions
Determine the number of atoms in 15 grams of water.

12. Empirical Formulas

13. Empirical Formulas
The simplest whole number ratio of moles of each element in the compound.
H2O
NaCl

14. Empirical Formulas
Usually given in percentages of each element in the compound.
Based on 100% of the compound.
Can be compared to a 100 gram sample of the substance.
11.2% Hydrogen
88.8% Oxygen

15. Empirical formula 1. Change percent to grams 11.2% H = 11.2 g H
88.8% O = 88.8 g O

16. Empirical formula
2. Convert grams to moles. (We know an empirical formula is the lowest whole number ratio of moles)
11.2 g H | 1 mol = mol
| 1.01 g
88.8g O | 1 mol = mol
| 16 g

17. Empirical formula
Cannot have decimals, the numbers must be whole numbers. Divide by the lowest.
11.2 g H | 1 mol = mol / = 2
| 1.01 g
88.8g O | 1 mol = mol / = 1
| 16 g
H2O = empirical formula

18. Empirical formula
36.84% N
63.16% O

19. Empirical formula
35.98% Al
64.02% S

20. Molecular Formula

21. Molecular Formula
Specifies the actual number of atoms of each element in one molecule or formula unit of the substance.

22. Molecular formula
1. The problem will give you a molar mass of the compound.
2. Calculate the empirical formula as usual.

23. Molecular formula 40.68% carbon 5.08% hydrogen 54.24% oxygen
Molar mass = g/mol

24. Molecular formula Change % to grams 40.68 g C | 1 mol = 3.387 mol
5.08 g H | 1 mol = mol
| 1.01 g
54.24 g O | 1 mol = mol
| 16 g

25. Molecular formula 3.387 mol / 3.387 mol = 1 x2 = 2
Empirical Formula = C2H3O2

26. Molecular formula To find the molecular formula:
(EFamu)x = MM (molar mass)

27. Molecular formula C2H3O2 = 59.05 = amu (59.05)x = 118.1 X = 2
(EF)x2 = (C2H3O2)x2 = C4H6O4

28. Molecular formula
65.45% C
5.45% H
29.09% O
MM = g/mol

29. Molecular formula
49.98 g C
10.47 g H
MM = g/mol

30. Molecular formula
46.68% N
53.32% O
MM = g/mol