CHEMICAL QUANTITIES

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CHEMICAL QUANTITIES

• All Roads Lead to the Mole

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Chemical Quantities
Dozen Baker as Mole Chemist

• Measuring doughnuts
• 1 dozen 12 doughnuts (count)
• 1 dozen 500 g doughnuts (mass)
• 1 dozen 1 box doughnuts (volume)

• Measuring steam (H2O gas)
• 1 mole 6.02 x 1023 H2O molecules (count)
• 1 mole 18.0 g H2O (mass)
• 1 mole 22.4 L H2O (volume) at STP

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Count Amedeo Avogadro

• 1776-1856
• Lawyer who became interested in math and physics
• Discovered that equal volumes of different gases
  contained an equal number of particles.
• 9 years after his death, Joseph Loschmidt
  determined a constant and named it after Avogadro.

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AVOGADROS CONSTANT 6.02 x 1023

• 1 mole 6.02 x 1023 particles
• 1 mole molar mass (grams)
• 1 mole (of a gas at STP) 22.4 L

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• The MOLE is to chemists
• as
• the DOZEN is to bakers.

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A Mole Balance
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Believe it or not, students all over the country
celebrate National Mole Day!
National Mole Day Foundation, INC. Mole Day
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5 Pound Bag of Sugar contains 6.6 moles Of
C12H22O11 1 Liter bottle of Water contains 55.5
moles H20 6.02 x 1023 Grains of Sand Would be
more than all of the sand on Miami Beach. 6.02 x
1023 Blood Cells Would be more than the total
number of blood cells found in every human on
earth. 6.02 x 1023 Watermelon Seeds Would be
found inside a melon slightly larger than the
moon. 6.02 x 1023 Pennies Would make at least 7
stacks that would reach the moon. 6.02 x 1023
Donut Holes Would cover the earth and be 5 miles
(8 km) deep.
How BIG is a MOLE?
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Draw on NOTETAKERS (and pass out flow Mole Map)
CARRY YOUR UNITS...
Mass
Volume
MOLE
R.P.
Molecules Atoms
Formula Units Ions
...AND YOUR UNITS WILL CARRY YOU!
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Types of Representative Particles

• Molecules (breaks down into atoms)
• Atoms
• Formula Units (breaks down into ions)
• Ions

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Naming Representative Particles
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Naming Representative Particles
Examples Name the representative particle for
each substance given. For each molecule, state
how many atoms are present. For each formula
unit, state how many ions make up the ionic
compound. H Cl2 C2H6 Cu(NO3)2 Al NaCl
ION
MOLECULE 2 ATOMS per molecule
MOLECULE 8 ATOMS
FORMULA UNIT 3 IONS per Form.U.
ATOM
FORMULA UNIT 2 IONS per Form.U.
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WS Representative Particles
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Mole R.P. Calculations
1 mole Avogadros Number 6.02 x 1023 R.P.s
R.P.
MOLE
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R.P. Example 1How many moles are in 1.4 x 1022
molecules of H2O?
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R.P. Example 2How many representative particles
are in 2.6 mol CO2?
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R.P. Example 3How many atoms are in 5.2 mol CO2?
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DO WS

• The Mole and Avogadros Number

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MOLAR MASS
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MASS of one MOLE
Gram atomic mass (gam) the atomic mass (the mass
in one mole of a substance) of an element
expressed in grams.
Gram molecular mass (gmm) the atomic
mass of one mole of a molecular compound. Gram
formula mass (gfm) the sum of the atomic masses
of the atoms that are in the formula of a
compound.
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gam, gfm, gmm examples

• Problem Give the gram atomic mass of hydrogen.
• Solution H 1H 1(1.01) 1.01 g/mol
• Problem Give the gram molecular mass of
  hydrogen.
• Solution H2 2H 2(1.01) 2.02 g/mol
• Problem Find the gram formula mass for H2SO4.
• Solution H2SO4 2H 1S 4O
• 2(1.01) 32.06 4(16.00) 98.08 g/mol

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Molar Mass a.k.a. Molecular Weight (MW)

• molar mass mass of 1 mole of substance
• Molar mass can be determined by adding up the
  atomic masses from the periodic table (atomic
  mass goes to 2 decimal places).

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MW Example 1

• Find the MW of CH4.
• 1C 4H
• 12.01 4(1.01)
• 16.05 g/mol

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MW Example 2

• Find the MW of Mg(OH)2.
• Mg 2O 2H
• 24.31 2(16.00) 2(1.01)
• 58.33 g/mol

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MW Example 3

• Find the MW of MgSO47H2O.
• Mg S 4O 7(H2O)
• 24.31 32.07 4(16.00) 7(1.011.0116.00)
• 246.52 g/mol

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WS Molar Mass (back side of R.P)

• Do 1-10

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• Calculations
• Use Mole Map to help calculate

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Mole Mass Calculations
1 mole molar mass (MW) in grams
Mass
MOLE
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Mass Example 1
Mass Example 1 How many grams are in 7.20 moles
of dinitrogen trioxide?
Dinitrogen trioxide N2O3
MW of N2O3 2N 3O 2(14.01) 3(16.00)
76.02 g/mol 1 mole 76.02 g N2O3
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Mass Example 2
Mass Example 2 Find the number of moles in 92.2
g of iron(III) oxide, Fe2O3.
Iron (III) oxide Fe2O3
MW of Fe2O3 2Fe 3O 2(55.85) 3(16.00)
159.70 g/mol 1 mole 159.70 g Fe2O3
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Mole Volume Calculations
1 mole 22.4 L of gas at STP STP standard
temperature and pressure (0 C 1 atm)
Volume
MOLE
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Volume Example 1
Volume Example 1 Determine the volume, in
liters, of 0.600 mol of SO2 gas at STP.
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Volume Example 2
Volume Example 2 Determine the number of moles
in 33.6 L of He gas at STP.
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Density
Density Mass / Volume When given the density of
an unknown gas, one can multiply by the molar
volume to find the MW. The MW can allow for
identification of the gas from a list of
possibilities.
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Density Example (part A)
The density of an unknown gas is 2.054 g/L at
STP. (a) What is the molar mass?
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Density Example (part B)
The density of an unknown gas is 2.054 g/L.
(b) Identify the gas as either
nitrogen, fluorine, nitrogen dioxide, carbon
dioxide, or ammonia. MW 46.01 g/mol (from
part a)
Nitrogen N2 2(14.01) 28.02 g/mol Fluorine
F2 2(19.00) 38.00 g/mol Nitrogen dioxide
NO2 14.01 2(16.00) 46.01 g/mol Carbon
dioxide CO2 12.01 2(16.00) 44.01
g/mol Ammonia NH3 14.01 3(1.01) 17.04
g/mol
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Mixed Mole Conversions
1 mole 6.02 x 1023 RPs MW 22.4 L of gas
_at_STP All Roads Lead to the Mole. Always convert
to units of moles first when converting between
grams, liters, and representative particles.
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Mixed Mole Example 1
How many carbon atoms are in a 50.0-carat
diamond that is pure carbon? Fifty carats is the
same as 10.0 g.
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Mixed Mole Example 2
How many atoms are in 22.0 g of water?
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Extra questions to review concepts
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What is the mass of one mole of table salt (NaCl)?

1. 23.0 g
2. 35.5 g
3. 58.44 g
4. 100.0 g

Atomic mass Na 22.99 g/mol Atomic mass Cl
35.45 g/mol Mass of one mole of NaCl 22.99
35.45 58.44 g
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What is the mass of 3.7 moles of NaCl?

1. 15.8 g
2. 58.5 g
3. 220 g
4. 6.02 x 1023 g

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What is the mass of one mole of water (H2O)?

1. 3.0 g
2. 16.0 g
3. 17.0 g
4. 18.02 g

Atomic mass H 1.01 g/mol Atomic mass O 16.02
g/mol Mass of one mole of H2O 2(1.01) 16.00
18.02 g
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How many moles are in 152 g of water?

1. 0.118 mol
2. 8.44 mol
3. 2736 mol
4. 6.02 x 1023 mol