THE MOLE
The Mole
an amount of substance.
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Intro to Mole Video
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Intro to the Mole Candy Activity
Part 1 - Particles
What is a mole?
standard counting unit in chemistry (abbreviated
“mol”)
Relates # particles, mass, and volume of gases
YOUR NEW BEST FRIEND THE MOLE CIRCLE!!!
PARTICLE PLACE
Relates the mole to the number of particles
CONVERSION FACTOR:
1 MOLE = 6.02 x 1023 Particles
MOLES AND PARTICLES
6.02 X 1023 is also known as Avogadro’s Number
Named after Italian chemist Amadeo Avogadro who
determined that at the same temp and pressure, all
gasses contained the same number of particles
Examples of Particles (Amount):
Charged Particles
Ions
Atoms
Li+, Ni2+, S2-, N3PO43-, OH-, NH4+
Particles of Ionic Compounds
Formula Units
Molecules
NaCl, CaSO4,
Fe(OH)3, AgNO3
What is a formula unit?
Molecular Compound
CO2
Molecules
Formula Unit
NaCl
Na+Cl-Na+Cl-Na+ClCl-Na+Cl-Na+Cl-Na+
Na+Cl-Na+Cl-Na+Cl-
smallest whole # ratio
of ions in the cmpd.
How many molecules are in 1 mole of molecules?
Pull
6.02 x 102
molecules
How many formula units are in 1 mole of formula units?
Pull
How many atoms are in 1 mole of atoms?
Pull
How many ions are in 1 mole of ions?
Pull
1 new conversion factor
YOU need to know.
1 mole = 6.02 x 1023 particles
Mole Circle!!!! Particle
Place
SO....back to Dim Analysis
Every problem must include for given, conversion factors
and answer:
Example: 6.02 x 1023 atoms Fe
Number
Substance
Unit
Use units - they must cancel
Answer in correct significant figures
Solving Mole Problems
1. Identify and label Given and Unknown.
2. Write down given x __________.
3. Put units of given on bottom of first conversion factor.
4. Use mole circle to figure out where you are starting, where you are going,
how many steps and conversion factors to get you there.
5. Set up using dimensional analysis - number, unit, substance for each entry.
Make sure units cancel along the way.
6. Multiply all items in numerator. Divide by numbers in denominator.
7. Answer - sig figs, units.
SO....back to Dim Analysis
How many atoms are in
3.4 mol of barium atoms?
2.05 x 1024 atoms
3.4 mol
6.02 x 1023 atoms
1 mol
= 2.05 x 1024 atoms
And...
How many mols of iron
5.6 x 1022 iron atoms?
are in
0.93 mol Fe
5.6 x 1022 atoms
1 mol
6.02 x 1023 atoms
= 0.093 mol
How many oxygen atoms
are in 2.2 mol of BaCO3?
3.97 x 1024 O atoms
2.2 mol BaCO3
6.02 x 1023 f.u. BaCO3
1 mol BaCO3
3-O atoms
1 f.u. BaCO3
=
How many carbon atoms are in a mixture of 2.0 mol of
CO2 and 3.5 mol of C6H12O6?
2.0 mol CO2
6.02 x 1023 CO2
molecules
1 mol CO2
1 C atom
=
1 CO2 molecule
1.2 x 1024 C atoms
3.5 mol C6H12O6
6.02 x 1023 C6H12O6
molecules
1 mol C6H12O6
1.26 x 1025 C atoms
+
1.2 x 1024 C atoms
1.26 x 1025 C atoms
1.38 x 1025 C atoms
6 C atoms
1 C6H12O6
molecule
=
Intro to the Mole Candy Activity
Part 2 - Mass
MASS AVE.
Do you know how to measure out 1 mole of sugar or salt or water?
The mole is a counting unit, so we would have to count out 6.02 x
1023 particles of each substance. (NO THANKS!)
There are 2 ways to measure out a number of moles of a
substance:
Measure it in GRAMS ( a mass)
If a GAS, measure it in LITERS ( a volume)
MASS AVE.
Relates the mole to the mass of one mole of
substance
CONVERSION FACTOR:
1 MOLE = Molar Mass of Substance
Molar Mass/Atomic Mass/Gram Formula
Mass/Molecular Weight
TAKE OUT YOUR PERIODIC TABLE :)
Molar Mass
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M
F
Molar mass
Pull
The mass of 1 mole
of substance.
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Atom
Atomic Mass
Carbon
12.011
Mg
24.03
Au
196.97
1 mol of Carbon = 12.011 g
1 mol Mg = 24.03 g
1 Mol Au = 196.97 g
Pull my Finger
Hey that's a NEW conversion factor!
1 mol = molar mass of substance
Molar Mass of a compound
Pull
Simply find the molar mass
of each atom
and add them together.
What is the molar mass of NaCl?
Na = 23 g
Pull
C
+l = 35.5 g
58.5 g
1 mole of NaCl has a mass of 58.5 g
Pull
What is the molar mass of K2SO4?
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What is the molar mass of Ca(OH)2?
Pull
1 mol Ca = 40g x 1 = 40g
1mol O = 16g x 2 = 32g
1mol H = 1g x 2 =
2g
+
74g
Mole to Mass and Mass to Mole Problems (same
process as mole to particles, particles to mole!)
How many grams of Al are in 3.00 moles of Al?
Answer = 80.94 = 80.9 g Al
What is the mass in grams of 2.7 mol of O2?
Answer = 86.4 = 86 g O2
Determine the number of moles in 5.00 g of H2O.
Answer = 0.277469 = 0.277 mol of H2O
Multi-Step Problems - Use the Mole Circle! Everything
MUST go through the Mole!!!
Calculate the number of grams of Na
present in 3.00 x 1018 atoms of Na:
= 0.0001146 g or 1.146 x 10-4 g of Na
Calculate the number of atoms of Na in
160.00 grams of Na:
= 4.189 x 1024 atoms of Na
Penicillin, the first of a now
large number of antibiotics,
has the formula
C14H20N2SO4. Calculate
the mass of
2.0 x 1010
molecules of penicillin.
Molar mass C14H20N2SO4 = 312.4 grams
2.0 x 1010
molecules of penicillin
= 1.0 x 10-11 grams of penicillin
Molar mass C14H20N2SO4 = 312.4 grams
2.0 x 1010
molecules
1 mol
6.022 x
1023
molecules
312.4
grams
1
mo l
= 1.04 x 10-11 grams of penicillin
(0.5 mg) (3) = 1.5 mg
molar mass caffeine = 194.2 grams
1.5 mg
1g
1 mol
6.022 x 1023
molecules
1000 mg
194.2 g
1 mol
= 4.65 x 1018 molecules of caffeine
How many atoms of carbon
would be in 53.5 grams of
isopentyl acetate (C7H14O2) ?
Percent Composition
Pull
% by mass of elements in a compound.
Mass of the Part
x 100 = % comp
Mass
of Element
Mass
of the Whole
Pull
Molar Mass of Compound
To solve: Assume 1 mole of compound.
can use.....
Then you
Find the % composition of water.
1- Determine the formula of the compound and list its elements.
Divide the molar mass
2g
H element by the
of each
=
0
.11g
18g
molarH2O
mass of the entire cmpd.
3-
0.11g x 100 = 11% H
0.89g x 100 = 89% O
Find the % composition when 8.20g of Mg combines with
5.40g of O.
+
8.20g Mg
5.40g O
13.60g MgO
8.20g Mg
13.60g MgO
x 100
5.40g O
13.60g MgO
x100
= 60.3%
= 39.7%
Mg
O
Empirical Formulas
Pull
Examples of Empirical Formulas
H2O
H3PO4
CH
H2O2
C6H12O6
Not necessarily the "actual"
formula!
Molecular Formulas
Pull
Cmpd.
Empirical
Formula
Molecular
Formula
formaldehyde
CH2O
CH2O
CH2O
acetic acid
CH2O
C2H4O2
C2H4O2
glucose
glucose
CH2O
C6H12O6
How to Calculate Empirical Formulas
Pull
Step 1.
Find the number of moles of each element.
Pull
(If % is given,
Step
2.100g of compound;
assume
% = grams)
Divide number of moles of each element by
smallest number of moles.
Step 3.
Pull
(finding ratio of # moles of each)
Find the lowest whole number ratio. Write
formula with subscripts reflecting ratio.
An alkaline battery contains 63.0 % Mn and 37.0% oxygen by
mass. Find the empirical formula of the cmpd.
An unknown cmpd was analyzed and found to contain
26.56% K, 35.41% Cr, 38.03% O. Find the empirical
formula for the compound.
Calculating Molecular Formulas
Pull
Pull
Pull
Molar mass of unknown molecular formula will be given to you!!!
S
D
m
Pull
ra
Calculating Molecular Formulas
1. The empirical formula of a compound is NO2. Its molecular
mass is 92 g/mol. What is its molecular formula?
2. A compound is found to be 40.0% carbon, 6.7% hydrogen
and 53.5% oxygen. Its molecular mass is 60.0 g/mol. What is
its molecular formula?
Calculating Molecular Formulas:
Step 1: Find the empirical formula mass.
Step 2: Divide molar mass by emp. formula mass.
Step 3: multiply answer from step 2 by the empirical formula
(how? multiply subscripts!)
What is the molecular formula if it's molar mass is 60 g/mol and
it's emp. formula is
CH4N?
mass is expressed in grams
Particles are atoms, ions, molecules and formula units.
1 mol = 6.02 x 1023 particles
1 mol = molar mass
If you can convert mass to mols you can then
convert mols to particles.
If you can convert particles to mols you can convert
mols to mass.
Attachments
Mole Circle Link.docx