1. 5.2 Mass and The Mole Learning Goals …
… determine the molar mass (M) of an atom or molecule
… use the formula m = n x M to solve for an unknown value
… answer two step problems involving two formulas

2. Molar Mass (M) – mass of 1 mole of substance (g/mol)
State the molar mass of the following:
(a) Copper ________________
(b) phosphorus ________________
(c) H2O ________________
(d) H2SO4 ________________
(e) Fe(NO3)3 ________________
63.55 g/mol
30.97 g/mol
18.02 g/mol
2 x
98.09 g/mol
2 x x 16
g/mol
x x 16

3. 𝑛= 𝑚 𝑀 FORMULA: m = mass (g) n = number of moles (mol)
M = Molar Mass (g/mol)
𝑛= 𝑚 𝑀
m n N atoms

4. Ex. Calculate the number of moles of 29.0 g of NaCl
m = 29.0 g
M = g/mol
n = ? mol
n = m ÷ M
= (29.0 g) ÷ (58.44 g/mol)
= mol
 There are mol of NaCl.
m  n

5. Ex. Calculate the mass of 8.61x1021 molecules of KOH.
m  n  N
N = 8.61x1021 molecules
M = g/mol
m = ?
n = N / NA
n = (8.61x1021 molecules)/(6.02 x 1023 molecules/mol)
= mol
m = n x M
= ( mol)(56.11 g/mol)
= g
 The mass of KOH is g.

6. Ex. How many chlorine atoms are in 320.0 g of Iron (III)chloride?
FeCl3
m = g
atoms = ?
M = g/mol
n = m / M
= (320.0 g) / (162.2 g/mol)
= mol
N = n x NA
N = ( mol)(6.02 x 1023 molecules/mol)
= x 1024 molecules
# atoms = N x 3 Cl atoms/molecule
= x 1024 Cl atoms
 There are x 1024 Cl atoms in g of FeCl3
m  n  N  atoms
3 Cl atoms

7. HOMEWORK p235 #36-39 p237 #46-49 p239 #56-59 p242 #61,62 CAN I …
… determine the molar mass (M) of an atom or molecule
… use the formula m = n x M to solve for an unknown value
… answer two step problems involving two formulas
HOMEWORK p235 #36-39 p237 #46-49 p239 #56-59 p242 #61,62