All Roads Lead to Mole City

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All Roads Lead
to Mole City
1
What Have We Learned
Thus Far (10.1)
How to convert from
molecules to moles/moles
to molecules
2
Molecules to Mole ….
If you have 7.36 x 1022 molecules of barium
sulfate, how many moles of BaSO4 do you
have?
7.36 x 1022
molecules BaSO4
1 mole BaSO4
6.02 x 1023
molecules BaSO4
= 0.122 mole
BaSO4
Molecules / Avogadro’s # = Moles
3
Moles to Molecules….
4
If you have 0.632 moles of barium sulfate,
how many molecules of BaSO4 do you have?
0.632
moles BaSO4
6.02 x 1023
molecules BaSO4
1 mole BaSO4
= 3.80 x 1023
molecules BaSO4
Moles x Avogadro’s # = Molecules
What Have We Learned
Thus Far (10.1)
How to calculate the
molar mass of a
compound
5
6
For instance ….
What is the molar mass of CuHAsO3?
Cu = 1(63.5)
H = 1(1.0)
As = 1(74.9)
O = 3(16.0)
=
=
=
=
63.5 g/mol
1.0 g/mol
74.9 g/mol
48.0 g/mol
= 187.4 g/mol
What Have We Learned
Thus Far (10.2)
How to convert from
grams to moles/moles
to grams
7
Grams to Moles ….
If you have 12.212 g of CuHAsO3.
How many moles do you have?
12.212 g CuHAsO3 1 mole CuHAsO3
187.4 g CuHAsO3
Cu = 1(63.5) = 63.5
H = 1(1.0) =
1.0
As = 1(74.9) = 74.9
O = 3(16.0) = 48.0
= 187.4 g/mol
= .065165421
mole CuHAsO3
= .06517 mole CuHAsO3
= 6.517 x 10-2 mole CuHAsO3
Grams / Molar Mass = Moles
8
Moles to Grams ….
9
If you have 1.54 moles of CuHAsO3.
How many grams do you have?
1.54 mol CuHAsO3 187.4 g CuHAsO3
= 288.596 g CuHAsO3
1 mole CuHAsO3
Cu = 1(63.5) = 63.5
H = 1(1.0) =
1.0
As = 1(74.9) = 74.9
O = 3(16.0) = 48.0
= 187.4 g/mol
= 289 g CuHAsO3
(only 3 sig figs)
Moles x Molar Mass = Grams
10
Delayed Objective (10.2)
Learn how to convert
between moles and
volume (L, gas)
We will learn this when we
derive the Ideal Gas Law in
Chapter 14.3, but …… just
multiply or divide by 22.4 L
All Roads Go Through Mole City
11
Molecule
Town
Divide by
molar mass
Mole City
Gas Station
Multiply by
molar mass
Gramville
Sample mixed mole problem:
Molecules to Grams
If you have 3.45 x 1025 molecules of NH3,
how many grams do you have?
3.45 x 1025
molecules NH3
1 mol NH3
6.02 x 1023
molecules NH3
17.0 g NH3
1 mol NH3
N = 1(14.0) = 14.0 g/mol
H = 3(1.0) = 3.0 g/mol
molar mass NH3 = 17.0 g/mol
= 974.252 g NH3
= 974 g NH3
12
Sample mixed mole problem:
Grams to Molecules/Atoms
13
If you have 66.23 g of CO2, how many
oxygen atoms do you have?
66.23 g CO2
1 mol CO2
44.0 g CO2
6.02 x 1023
molecules CO2 2 atoms oxygen
1 mol CO2
1 molecule CO2
= 1.8123 x 1024 oxygen atoms
C = 1(12.0) = 12.0 g/mol
O = 2(16.0) = 32.0 g/mol
molar mass CO2 = 44.0 g/mol
= 1.81 x 1024 oxygen atoms
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