1. Chemical Quantities
Chapter 7

2. Representative Particles
The smallest divisible unit of a substance
Elements – Atoms
Molecular Compounds – Molecules
Ionic Compounds – Formula Units
Part of a Molecular Compound –
Atom
Part of an Ionic Compound - ion

3. The Mole Quantity equal to 6.022 x 1023 representative particles.
A.k.a
Avogadro's Number

4. How big is a mole?
A mole of hockey pucks is equal to the mass of the moon.

5. How big is a mole?
A mole of rice would occupy a cube with sides of about 120 miles!

6. How big is a mole?
A mole of rice grains is more grains then the number of grains of all grain grown since the beginning of time!

7. How big is a mole?
If you had a mole of pennies, you could buy kite string at a million dollars an inch. With this string you could wrap it around the earth a million times and to the moon and back 25 times. You could sell the left over string back at a penny an inch ( a major loss) and take the remaining money and give everyone in the world about $10,000.

8. O.K. seriously…How big is a mole?
How much is a mole of water molecules?
Let me show you!

9. Now for some math…
How many moles is 3.78 x 1022 atoms of magnesium?

10. Example 2
How many moles is 3.78 x 1022 molecules of sulfur dioxide?

11. Example 3
How many moles is 1.80 x 1021 formula units of sodium sulfate?

12. Example 4
How many atoms in moles of zinc?

13. Example 5
How many molecules in moles of carbon dioxide?

14. Example 6
How many formula units in 1.22 moles of iron (III) chloride?

15. Example 7
How many atoms of hydrogen are in 5.15 mol of methane (CH4)?

16. Example 8
How many ions of potassium are in 0.80 mol of potassium carbonate?

17. Example 9
How many ions of nickel are in 0.80 mol of nickel (II) oxalate?

18. Molar Mass
Chapter 7

19. Molar Mass The mass in grams of one mole of substance.
Older terms you might hear
Molecular weight
Formula weight

20. Calculating Molar Mass
Use the atomic masses on the periodic table.
On many of them you can round to the nearest gram, except for elements that atomic masses end in 0.5
Use as many significant figures needed to maintain the number of significant figures given in the problem.

21. Example 1
What is the molar mass of selenium?
mm = g/mol

22. Example 2 What is the molar mass of nitrogen gas (N2)?
mm = 2 x 14.0 = 28.0 g/mol

23. Example 3 What is the molar mass of water (H2O)? H 2 x 1.0 = 2.0
O 1 x 16.0 = 16.0
mm = 18.0 g/mol

24. Example 4 What is the molar mass of Tin (II) Chloride? SnCl2
Sn 1 x 119 = 119
Cl 2 x 35.5 = 71
mm = 190 g/mol

25. Representative Particles
Mole Map
Mole
Periodic Table
Molar Mass
Avogadro's Number
6.022 x 1023
Mass (g)
Representative Particles
Molecules
Formula Units
Atoms
Atoms
Ions

26. Example 5
How many atoms are in 5.6 mol of iron?

27. Example 6
How many grams are in 5.6 mol of iron?

28. Example 7
How many atoms are in 5.6 g of iron?

29. Example 8
How many grams does 3.4 x 1024 atoms of Sodium weigh?

30. Example 9
How many moles is 125 g of calcium?

31. Empirical and Molecular Formulas
Chapter 7

32. H2O2 (molecular formula) = HO (empirical formula)
A formula with the lowest whole number ratio of elements.
Examples
H2O2 (molecular formula) = HO (empirical formula)
H2O = H2O
C12H22O10 = C6H11O5
Several different formulas can yield the same empirical formula.

33. Steps for solving empirical formula problems
Convert grams to moles. (If in percent, treat as grams.)
Divide by lowest mole.
If not in whole number ratio, multiply by a common whole number to get a whole number ratio.

34. Example 1
Find the empirical formula of a compound that is 25.9g N and 74.1g O.

35. Example 2
1.58 g of copper was reacted with sulfur to produce a compound with a mass of 1.98 g. What is the empirical formula for the compound?

36. Example 3
Find the empirical and molecular formula of a compound that is 67.6% Hg, 10.8% S and the balance O. The molar mass of the compound is 891 g/mol.

37. Molar Volume
Chapter 7

38. Molar Volume The volume of one mole of a gas.
At STP, the volume of one mole of gas is 22.4 L
STP = standard temperature and pressure
Standard Temperature = 0oC
Standard Pressure = 1 atm
Atm = atmosphere

39. Representative Particles
Mole Map
Volume (L)
At STP 1 mole = 22.4L
Mole
Periodic Table
Molar Mass
Avogadro's Number
6.022 x 1023
Mass (g)
Representative Particles
Molecules
Formula Units
Atoms
Atoms
Ions

40. Example 1
What is the volume of 0.60 moles of SO2 at STP?

41. Example 2
What is the volume in mL of 90 g of SO2 at STP?

42. Percent Composition
Chapter 7

43. Percent Composition
Percent by mass of elements in a compound.

44. Example 1
Find the percent composition of potassium chromate.

45. Example 2
What is the percent sodium in sodium fluoride?

46. Example 3
How many grams of a 40 g sample of sodium fluoride is sodium?