Review: Molar Mass of Compounds

1
Review Molar Mass of Compounds

• Ex. Molar mass of CaCl2
• Avg. Atomic mass of Calcium 40.08g
• Avg. Atomic mass of Chlorine 35.45g
• Molar Mass of calcium chloride 40.08
  35.45(2) _110.98______ g/mol CaCl2

20 Ca  40.08
17Cl 35.45
2
Practice

• Calculate the Molar Mass of calcium phosphate
• Formula
• Ca3(PO4)2
• Masses elements
• Ca 40.08g/mole
• P 30.97 g/mole
• O 16.00 g/mole
• Molar Mass
• (40.08 g/mole)(3) (30.97 g/mole)(2) (16
  g/mole)(8)
• 310.18 g/mole

3
Mole Conversions

• Learning Target
• Understand how molar mass relates to the number
  of moles and particles of a substance.

4
Particles (atoms, Formula units, molecules)
Divide by 6.02 X 1023
Multiply by 6.02 X 1023
Moles
Multiply by molar mass from periodic table
Divide by molar mass from periodic table
Mass (grams)
5

• 3.5 dozen roses ?? Roses
• 2.5 mol roses ?? Roses (use Avogadro's )

6
Problem Type 1 Moles to Mass

• Find the mass of 0.760 mol of magnesium bromide..
• Find the molar mass of the compound
• Make the conversion

7
Problem Type 2 Mass to Moles

• A bottle of copper (II) nitrate contains 110.6 g
  of compound. How many moles of copper (II)
  nitrate are in the bottle?

8
Problem Type 3 Moles to Particles

• Determine the number of atoms that are in 0.78
  mol of mercury.

9
Problem Type 4 Particles to Moles

• How many moles of zinc sulfate contain 5.40 x
  1024 formula units?

10
Multi-step Mole Conversions

• 2.5 g Roses ?? atoms of roses
• Atomic mass of 1 Rose is 3.0 g/mol

11
Multi-step Practice

• How many molecules are in 7.4 g of potassium
  phosphate?

12
Multi-step Practice

• How many grams of sodium bicarbonate are in 1.8 x
  1023 formula units?

13
Molar Volume

• Definition The volume of one mole of an ideal
  gas at standard conditions (STP) equal to 22.4 L.
• STP standard temperature and pressure which is
  0ºC and 1 atmospheric pressure (760 mmHg)
• 1 mole gas at STP 22.4 L

14
Particles (atoms, Formula units, molecules)
Divide by 6.02 X 1023
Multiply by 6.02 X 1023
Moles
Multiply by 22.4 L
Divide by 22.4 L
Volume (L)
15
Practice

• A container with a volume of 563L contains how
  many moles of air at STP?
• How many molecules of air?

16
Practice

• A chemical reaction produced 0.78 mol of H2 gas.
  What volume will the gas occupy at STP?
• How many molecules of H2?
• How many atoms of hydrogen?