Review: Molar Mass of
Compounds

Ex. Molar mass of CaCl2
20
Avg. Atomic mass of Calcium = 40.08g
 Avg. Atomic mass of Chlorine = 35.45g


Ca
40.08
17
Cl
35.45
Molar Mass of calcium chloride =
40.08 + 35.45(2) = _110.98______ g/mol CaCl2
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
Mole Conversions
Learning Target:
Understand how molar mass
relates to the number of moles
and particles of a substance.
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)

3.5 dozen roses = ?? Roses

2.5 mol roses = ?? Roses (use Avogadro's #)
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:
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?
Problem Type #3 – Moles to
Particles

Determine the number of atoms that are in
0.78 mol of mercury.
Problem Type #4 – Particles to
Moles

How many moles of zinc sulfate contain 5.40
x 1024 formula units?
Multi-step Mole Conversions

2.5 g Roses = ?? atoms of roses

Atomic mass of 1 Rose is 3.0 g/mol
Multi-step Practice

How many molecules are in 7.4 g of
potassium phosphate?
Multi-step Practice

How many grams of sodium bicarbonate are
in 1.8 x 1023 formula units?
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
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)
Practice

A container with a volume of 563L contains
how many moles of air at STP?

How many molecules of air?
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?