Moles
Stoichiometry
1. Stoichiometry - “measuring matter”
–
–
–
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Water contamination
Radon Levels
Hormone levels in milk
Impurities in computer chips
Moles
H vs He
He vs C
C vs Mg
Atomic Mass
Moles
Amadeo Avagadro’s Number
Mole- Standard Number of atoms
or molecules used by chemists
1 mole = 6.022 X 1023
atoms/molecule
Moles
Moles
Moles
Stoichiometry
Grams
Moles
1gH
1 mole H
Atoms
6.02 X 1023 atms
2gH
12 g C
3 mol C
36.12 X1023 atm He
Grams
Moles
Atoms
14 g N
42 g N
48 g C
2 mol Na
3 mol Be
36.12 X1023 atm O
30.10 X1023 atm Ca
12.04 X1023 atm Si
Moles
Stoichiometry
Rounding – 1 decimal place
Iron
55.845 g/mole  55.8 g/mol
Sulfur
32.066 g/mole  32.1 g/mol
Oxygen
15.9994 g/mole  16.0 g/mol
Moles
GMA
Grams
Moles
Atoms
1. How many Na atoms are present in 11.5 g
of Na? (Ans: 3.01 X 1023 atoms)
2. How many C atoms are present in 18.0 g?
(Ans: 9.03 X 1023 C)
Moles
GMA
3. What is the mass of 1.20 X 1024 atoms
of Na? (Ans: 45.8 grams)
4. What is the mass of 1.51 X 1023 atoms
of Be?(Ans: 2.26 g)
5. Start with 0.854 mole V
6. Start with 0.0570 mole Rn
Moles
How many grams and atoms are in 0.333 moles of
Sulfur?
Moles
Molar Mass
1. Molar Mass = mass of one mole
2. Units – grams/mole or amu (atomic
mass units)
3. What is the molar mass of:
1. C
2. O2
3. BaCl2
Moles
4. What is the molar mass of
Cu(NO3)2? (187.5 g/mol)
5. What is the molar mass of
Al2(SO4)3? (342.3 g/mol)
Molar Mass
Warm-Up
Find everything else if given:
a) 0.589 g Ne
b) 4.567 X 1024 atoms of K
c) 0.00845 mol of Ba
Calculate the molar mass of:
a) KrF4
b) Al(NO3)3
c) Calcium hydroxide
Warm-Up
Find everything else if given:
a) 0.589 g Ne (0.0292 mol, 1.76 X1022 atoms)
b) 4.567 X 1024 atoms of K (7.58 mol, 297 g)
c) 0.00845 mol of Ba (1.16 g, 5.09 X1021 atoms)
Calculate the molar mass of:
a) KrF4 (159.8 g/mol)
b) Al(NO3)3 (213.0 g/mol)
c) Calcium hydroxide (74.1 g/mol)
Moles
GMMA
1. Monoatomic Elements (C, Fe, Au)
GMA
2. Molecules and Ionics (H2O, CaCl2,
O2)
GMMA
3. You may see “Formula Units” instead
of “Molecules” for Ionic compounds
Moles
Moles
Grams
GMMA
Moles
Molecules Atoms
1 mole of Na
2 mole of Na
1 mole of H2O
1 mole of CH4
3 mole of CH4
Moles
GMMA
1. How many calcium and chlorine
atoms are in 200.0 grams of Calcium
Chloride?
2. How many hydrogen and oxygen
atoms are in 3.60 grams of H2O?
(Ans: 2.41 X 1023 atoms H)
Moles
GMMA
3. Given 0.345 mol of Al2(CO3)3, find
everything else.
4. Given 3.01X1024 molecules of SO3,
find everything else.
5. Given 9.42 X10 22 molecules of
C2H4, find everything else.
Moles
GMMA
6. What is the mass of 3.01 X 1022
molecules of Iron(III)Bromide?
(Ans: 14.8 g)
Moles
1. Given 0.810 g of Mg, find moles and
atoms. (0.0333 mol, 2.01X1022 atoms)
2. Given 3.47 X 1022 atoms of fluorine, find
grams and moles. (1.10 g. 0.0576 mol)
3. How many carbon atoms are in 36.0
grams of C2H6? (Ans:1.45 X 1024 atoms
of C)
4. How many carbon atoms would be needed
to weigh the same as one Titanium atom?
Moles
Mixed Examples
1. How many carbon atoms are in 36.0
grams of carbon? (1.81 X 1024)
2. How many carbon atoms are in 36.0
grams of C2H6? (Ans:1.45 X 1024
atoms of C)
Moles
Mixed Examples
Warm-Up Problems (find everything else)
a) 10.0 g C
b) 10.0 g C2H6
c) 4.00 X 1023 atoms of S
d) 4.00 X 1023 molecules of SO2
e) 0.440 moles of SO2
Grams
Moles
10.0 g C
0.833
Molecules
Atoms
Mixed Examples
========
5.02 X 1023
1023
4.02 X 1023 C
12.1 X 1023 H
10.0 g C2H6
0.333
2.01 X
21.3 g S
0.664
========
4X1023 S
42.6 g SO2
0.664
4X1023 SO
28.2 g SO2
0.44 SO2
2.65 X 1023
4 X 1023 S
8 X 1023 O
2.65 X 1023 S
5.30 X 1023 O
164.1 g/mol
71.0 g/mol
197.0 g/mol
106.8 g/mol
2
234.0 g/mol
Moles
Percent Composition
1. Definition - % of the elements in a
compound by mass
2. Class Example
Girls
12
Boys
13
Moles
Percent Composition
1. What is the % composition of CaCl2?
(Ans: 36.1 %, 63.9%)
2. What is the % composition of C2H5OH?
(Ans: 52.2 %, 13.0 %, 34.8 %)
3. What is the % composition of Al2(SO4)3?
(Ans: 15.8 %, 28.1 %, 56.1 %)
Moles
Empirical Formula
1. Definition – The simplest ratio of the
elements in a compound
2. Class with
6 girls, 9 boys
Moles
Empirical Formula
3. Examples
Formula
C 2 H2
Al4S6
C6H12O6
C12H24O12
Empirical Form.
Moles
Empirical Formula
1. What is the EF of a compound that has
0.900 g Ca and 1.60 g Cl?
Rules
- Go to moles
- Divide by the smaller
Moles
Empirical Formula
2. What is the EF of a compound that is
40.0 % C, 6.67 % H and 53.3 % O?
3. What is the EF of a compound that is
66.0 % Ca and 34.0% P?
4. What is the EF of a compound that is
43.7 % P and 56.3 % O?
a. Write the formula of calcium nitrate.
b. Calculate the percent composition of calcium nitrate. (24.4% Ca, 17.1% N,
58.5% O)
c. A compound was analyzed and found to contain 13.5 g Ca, 10.8 g O, and
0.675 g H. Calculate the empirical formula of the compound? (CaO2H2
or Ca(OH)2)
d. A compound is 69.6% manganese, the rest is oxygen. Calculate the
empirical formula.
Moles
Molecular Formula
1. Empirical – Only tells you the
ratios of the elements
2. Molecular – Tells you the true
number of each element
Moles
EF
CH2O
Molecular Formula
MF
CH2O
C2H4O2
C3H6O3
C4H8O4
(30 g/mol)
(60 g/mol)
(90 g/mol)
(120 g/mol)
Moles
Molecular Formula
1. What is the MF of benzene if it has an
EF of CH and a molar mass of 78.0
g/mol?
2. What is the MF of a compound if it has
an EF of AgCO2 and a molar mass of
304.0 g/mol?
Moles
Molecular Formula
3. What is the MF of a compound that is
40.9% C, 4.58 % H and 54.5 % O? It
has a molar mass between 350 and 360
g/mol.
4. What is the MF of a compound that
contains 4.90 grams of N and 11.2 g of
O? The molar mass is about 90 g/mol.
1. 33.9% Cu, 14.9% N, 51.2% O
Moles
2. 57.5% Na, 40.0% O, 2.5% H
3. 36.1% Ca, 63.9% Cl
4. 70% Fe, 30% O
5. 32% Fe, 27.6% C, 3.5% H, 36.8% O
6. 37.4% Cu, 62.6% Cl
7. 80.2% Ba, 18.7% O, 1.2% H
8. 25.9% N, 74.1% O
9. 60% Ti, 40% O
10.39.8% Cu, 20.1% S, 40.0% O
CaO
NH3
AlI3
KI
SO2
K2Cr2O7
N2H8SO4
AgNO3
KMnO4
N2H4O3
H2SO4
NaNO3
H3PO4
C8H8O3
As2O3
C2H2O4
C8H16O4
C2H6
C2H4Cl2
C6H4Cl2
N 2O 4
15 grams
Moles
mol
atoms
a) 0.390
0.017
1 X 1022
b) 1.57 X 106 3.01 X 104
1.81 X 1028
c) 43.2 (Boron) 4.00
2.41 X 1024
d) 4.25 X 10-6 1.09 X 10-7
6.55 X 1016
e) 0.123
6.08 X 10-3
3.66 X 1021
17 a) 41.0 g
b) 400. g
c) 3.67X106g
19 a) 10.0 mol b) 122 mol
c) 3.16X10-23mol
26. a) 267.6 g/mol b) 119.0 g/mol c) 318.0 g/mol
d) 103.8 g/mol e) 220.0 g/mol
30 Grams
Moles
Moles
3.67
3.75 X 10-3
2.5 X 10-22
0.141
Molecules
2.21 X 1024
2.26 X 1021
150
8.50 X 1022
a) 176
b) 0.173
c) 3.0 X 10-20
d) 49.7
32.46.7 g/mol
46 a) 3.2%, 19.4%, 77.4%
b) 38.8%, 61.2%
c) 12.7%, 19.7%, 67.6%
d) 12.2%, 5.2%, 27.0%, 56.6%
48 63.6%, 6.0%, 21.2%, 9.3%
Moles
57. a) SiO2
59.K2S2O3
61.NH3C3
64.Na2CrO4
67.C3N3O9H5
69. N4S4
72.C6H12O6
88.K2C2O6
b) C2S
c) X5Y6
d) Fe2C3O9
Calculate the empirical formula of a compound
Moles
that contains 55.3 grams of potassium, 14.6 g of
phosphorus, and 30.1 g of oxygen.
1. Make up a compound containing 3 elements
Moles
1. No subscripts >5
2. Use both even and odd numbers
3. Ex: C3O5F2
2. Calculate the percent composition of your
imaginary compound. Also calculate the molar
mass. Write these numbers down on an index
card.
3. Give your card to another group. See if they can
determine the formula of your compound.
Moles
Beware the
Mole
Man