Moles

Report
Topics covered to date:
• Topic 1 – Atoms
• Topic 2 – Formulas and Equations
• Topic 3 – Chemistry Math
• Topic 4 – Matter
• Topic 5 – Periodic Table
• Topic 6 - Bonding
You must choose 4 for mid-term
Stoichiometry
AKA Chemistry Math
BELL RINGER
“my avogadro don't want none unless you've got moles hun”
How many atoms are in
a mole of carbon?
Ridiculous Mole
Facts
3 moles of M&M’s would fill the
entire earths oceans (an
equivalent amount of water would
fill about a ¼ cup)
1 mole of donut holes will cover the
earth to a depth of seven miles!
1 mole of pennies would reach to
the moon 7-8 times.
Ridiculous Mole
Facts
One mole of seconds is about 19
quadrillion years, 4,240,666 times the
age of the earth, or 954,150 times the
age of the universe itself.
A one liter bottle of water contains
55.5 moles of water.
If you started with a mole of pennies and
spent $1,000,000 every second for 100
years, you would still have more than
99.99% of what you started with.
Are all moles created equally?
VS
In chemistry, how an atom reacts is dependent on the number of
atoms, not the mass of the atoms.
For example, if you have 100.0 g of Na and react that with 100.0 g of
Chlorine they would not react completely.
•Chlorine starts out with a mass of 35.5 and Na has a mass of 23
•As a result, we would have a bunch of Na atoms unused.
•In chemistry it is much easier to use a quantity of atoms rather than a
mass of atoms
A nice mole song!
Avogadro Style
Moles
What is the mass of a Carbon atom?
12.0 amu
If one mole of Carbon atom’s have a
mass of 12.0g, how many atoms
would that be?
That would be 6.02 x 1023 atoms of carbon
Gram
Formula
Mass
(molar mass)
= the mass of one mole of something
Let’s try out water:
H 2O
Therefore, 1 mole of
water has a mass
of 18g/mol.
H
2 x 1.0 = 2.0
O
1 x 16.0 = 16.0
18.0 g/mol
GFM
(practice)
Let’s try magnesium hydroxide: Mg(OH)2
Mg 1 x 24.3 = 24.3
O
2 x 16.0 = 32.0
H
2 x
1.0 =
2.0
58.3 g/mol
GFM - Hydrates
Hydrate - is a crystalline compound in
which ions are attached to one or
more WATER molecules
Sodium Carbonate crystals: Na2CO3●10H20
Na 2 x 23.0 = 46.0
C
0
1 x 12.0 = 12.0
3 x 16.0 = 48.0
H20 10 x 18.0 = 180.0
286.0 g/mol
BELL RINGER
“my avogadro don't want none unless you've got moles hun”
What is the gfm of NH4?
GFM = 18
Moles = 72.0 ÷ 18.0 = 4 moles
Converting
to moles
If you have 63g of water how many moles of
water do you have?
1. Determine the gfm:
Number of moles
Number of moles
18 g/mol
=
given mass (g)
gram-formula mass
=
63g
18g/mol =
3.5 moles
Conversions
Moles to Grams
1. How many g are in 0.0700 moles of H2O2?
Number of moles
=
given mass (g)
gram-formula mass
x
0 .0 7 0 0 m o le s 
3 4 .0 g /m o le
x  2 .3 8 g
2. How many g are in 1.20 moles of CaCO3?
x
1.20moles 
100.1g/mol e
x  120.mol
GFM Practice
1. NaBr
6. C6H12O6
2. PbSO4
7. Fe3(PO4)2
3. Ca(OH)2
8. (NH4)2S
4. Na3PO4
9. Zn(C2H3O2)2
5. (NH4)2CO3
10. AgF
GFM Practice
1. NaBr
102.9 g/mol
2. PbSO4
303.3 g/mol
3. Ca(OH)2
74.1 g/mol
4. Na3PO4
164.0 g/mol
5. (NH4)2CO3
96.0 g/mol
6. C6H12O6
180.0 g/mol
7. Fe3(PO4)2
357.4 g/mol
8. (NH4)2S
68.1 g/mol
9. Zn(C2H3O2)2
183.4 g/mol
10. AgF
126.9 g/mol
BELL RINGER
You have 72.0g of NH4. How
many moles do you have?
GFM = 18.0
Moles = 72.0 ÷ 18.0 =
4.00 moles
Some Practice
1. What is the gfm for Calcium nitrate?
Criss-cross to get the formula:
Ca(NO3)2
Ca 1 x 40.1 = 40.1
N 2 x 14.0 = 28.0
O 6 x 16.0 = 96.0
164.1 g/mol
2. How many moles of calcium nitrate do you have
if you have 10.2 g?
Number of moles
Number of moles
=
=
given mass (g)
gram-formula mass
10.2g
164.1g/mol
= 0.0622 moles
Practice Problems
1. If you have 40.8g of KClO3. How many
moles do you have?
Number of moles
Number of moles
=
given mass (g)
gram-formula mass
=
40.8 g
122.6g
GFM = 122.6 g
= 0.333 moles
2. You have 2.5 moles of KClO3. How many
grams is that?
GFM = 122.6 g
Grams = GFM x # moles
Grams = 122.6g/mol x 2.5 moles
= 306.5 g
= 310 g
Percent
Composition
-used to find the percentage by mass of an
element in a compound
% com p 
m a ss o f p a rt
x100
m a s s o f w h o le
What are the % of elements in dihydrogen
monoxide?
HO
2
H
O
2 x 1.0 = 2.0 %= 2.0/18.0 = 11%
1 x 16.0 = 16.0 %= 16.0/18.0 = 88.9%
18.0 g
Percent
Composition
What are the % of elements in potassium
nitrate?
KNO3
% com p 
m a ss o f p a rt
x100
m a s s o f w h o le
K
1 x 39.1 = 39.1
% = 39.1/101.1 = 38.7%
N
1 x 14.0 = 14.0
3 x 16.0 = 48.0
% = 14.0/101.1 = 13.8%
O
101.1 g
% = 48.0/101.1 = 47.5%
Percent
Composition
Hydrate
What is the percentage of water in the
CoCl2•6H2O
following compound
Co 1 x 58.9 = 58.9 % = 58.9/237.9 = 24.8%
Cl 2 x 35.5 = 71.0
H2O 6 x 18.0 = 108.0
% = 71.0/237.9 = 29.8%
% = 108.0/237.9 = 45.40%
237.9 g/mol
Percent
Composition
Hydrate
What is the percentage of water in the
following compound
CaSO4•5H2O
Ca 1 x 40.1 = 40.1
S
1 x 32.1 = 32.1
O
4 x 16.0 = 64.0
H2O 5 x 18.0 = 90.0
% = 90.0/226.2 = 39.8%
226.2 g/mol
BELL RINGER
How many grams is 0.36
moles of potassium
permanganate?
Empirical and
Molecular Formulas
Empirical Formula = the formula of a
compound expressed as the smallest
possible whole-number ratio of
subscripts of the elements in the formula
Molecular Formula = the formula of a compound
in which the subscripts give the actual number of
each element in the formula
Empirical and Molecular Formulas
Molecular Formula
Empirical Formula
H2O
H2O
CH3COOH
CH2O
CH2OH
CH2OH
WO2
WO2
B2H6
BH3
C6H12O6
CH2O
Empirical and Molecular Formulas
A compound with an empirical formula of
C2OH4 and a molar mass of 88 grams per
mole. What is the molecular formula of the
compound?
Empirical and Molecular Formulas
A well known reagent in analytical
chemistry, dimethylglyoxime, has the
empirical formula C2H4NO. If its molar
mass is 116.1g/mol, what is the molecular
formula of the compound?
BELL RINGER
What are the empirical
formulas for the following?
C6H6
CH2ClCH3
HC2H3O2
Determining Formulas from %
Percent to mass
Mass to moles
Divide by small
Multiply ‘til whole
A compound consists of 72.2% magnesium and 27.8%
nitrogen by mass. What is the empirical formula?
1. Assume 100g, so you have: 72.2g Mg and 27.8g N
2. Convert to moles
Mg - 72.2/24.3 = 2.97 moles
N – 27.8/14.0 = 1.99 moles
Determining Formulas from %
Percent to mass
Mass to moles
Divide by small
Multiply ‘til whole
3. Divide by small
Mg 2.97 / 1.99
N 1.99 / 1.99
= 1.49
= 1.00
Mg1.49N1.00 ???
4. Multiply ‘til whole
Mg 1.49 X 2 = 3
N 1
X2=2
Mg3N2
Hydrate Problem
• In lab, a student determined that a
hydrate of barium chloride contained
14.0% water. What is the actual
numbers of water molecules for
each molecule of barium chloride.
Basically the formula of the hydrate.
REMEMBER
Hydrate Problem
Barium
Chloride
Water
14.0%
BELL RINGER
Problem: A compound contains 32.4% sodium, 22.1%
sulfur and 45.0% oxygen. What is the empirical formula?
• Na
32.4g ÷ 23.0 = 1.41 mol
÷ .688
= 2.05
•S
22.1g ÷ 32.1 = 0.688 mol ÷ .688
= 1.00
•O
45.0g ÷ 16.0 = 2.81 mol
= 4.09
÷ .688
As a result the formula would be:
Na2SO4
Hydrate Practice
A calcium chloride hydrate has a mass of 4.72 g.
After heating for several minutes the mass of the
anhydrate is found to be
3.56 g. Use this information to determine the
formula for the hydrate.
Hydrate Practice (lab problem)
Mass of Hydrate = 4.72g
Anhydrous = 3.56g
Calcium
Chloride
Water
CHEMICAL REACTIONS
Reactants: Zn + I2
Product: Zn I2
Chemical Equations
Because of the principle of the law
conservation of matter,
an equation
must be
balanced.
It must have the same number of
each kind of atoms on both sides.
Lavoisier
1788
Chemical Equations
Their Job: Depict the kind of
reactants and products and their
relative amounts in a reaction.
4 Al (s) + 3 O2 (g) ---> 2 Al2O3 (s)
The numbers in the front are called
coefficients
stoichiometric ____________
Symbols Used in Equations
• Solid (s)
• Liquid (l)
• Gas (g)
• Aqueous solution (aq)
H2SO4
• Catalyst
• Escaping gas ()
• Change of temperature ()
Balancing Equations
When balancing a chemical reaction you
may add coefficients in front of the
compounds to balance the reaction but you may
not
change the subscripts.
Changing the subscripts changes the
compound. Subscripts are determined by
the valence electrons (charges for ionic
or sharing for covalent)
Subscripts vs. Coefficients
• The subscripts
tell you how
many atoms of
a particular
element are in a
compound. The
coefficient tells
you about the
quantity, or
number, of
molecules of
the compound.
Why are we learning this?
1.
The coefficients of a chemical reaction indicate
relative amounts of reactants and products.
Coefficients are MOLE RATIOS
Example: H2(g) + Cl2(g)  2HCl(g)
1 mol H2 : 1 mol Cl2 : 2 moles HCl
2.
The relative masses of the reactants and products can
also be determined from the coefficients.
Example:
1 mol H2 = 2.02 g H2
1 mol Cl2 = 70.90 g Cl2
2 mol HCl = 72.92 g HCl
Therefore, 2.02g H2 will react with 70.90g
Cl2 to form 72.92g of HCl.
Steps to Balancing Equations
1.Compare the numbers of atoms on each
side of the equation
2.Start with the most complicated
molecules FIRST!
3.Leave H and O until the end
4.Place COEFFICIENTS in front of the
compound to try and balance the atoms
5.Check your answer to see if:
- The numbers of atoms on both sides of the
equation are now balanced.
6.Reduce if possible!!!!
Steps to Balancing
Equations
2 Al(s) + ___
3 Br2(l) ---> ___ Al2Br6(s)
___
Online Balancing Equations
Click on picture above to go to the site!
Balancing
Equations
5
____C3H8(g) + _____
O2(g) ---->
3
4
_____CO
2(g) + _____ H2O(g)
2
11
____B
H
(g)
+
_____
O2(g) ---->
4 10
4 ___
2 B2O3(g) + 10
5
_____
H2O(g)
BELL RINGER
Balance the following:
Sodium phosphate + iron (III)
oxide  sodium oxide + iron
(III) phosphate
2 Na3PO4 + Fe2O3 ----> 3 Na2O + 2 FePO4
BELL RINGER
Balance the following:
Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O
• Balancing wkst
Practice Balancing Equations
2 + __O2  __Al2O2
__Al
3 2  __
2 FeCl3
2 Fe + __Cl
__
3 2SO4  __Fe2(SO4)3 + __H
3 2O
__Fe2O3 + __H
2
3
2
__KClO
3 → __KCl + __O2
Practice
Write out the following chemical equation 
Methane reacts with oxygen to produce carbon dioxide and water
CH4 + O2  CO2 + H2O
Practice
Write out the following chemical equation 
Hydrogen gas reacts in the presence of oxygen gas to explode
and produce liquid water.
H2(g) + O2(g)
H2O(l) +energy
BELL RINGER
What is the IUPAC name of
the following compound?
Mn2O3
Chemical Equations
4 Al(s) + 3 O2(g)
---> 2 Al2O3(s)
This equation means
4 Al atoms + 3 O2 molecules
---produces--->
2 molecules of Al2O3
AND/OR
4 moles of Al + 3 moles of O2
---produces--->
2 moles of Al2O3
Types of Reactions
There are five types of chemical reactions
we will talk about:
1.
2.
3.
4.
5.
•
Synthesis reactions
Decomposition reactions
Combustion reactions
Single replacement reactions
Double Replacement reactions
You need to be able to identify the type
of reaction and predict the product(s)
1. Synthesis Reactions
• Synthesis reactions occur when two
substances (generally elements) combine and
form a compound. (Sometimes these are called
combination or addition reactions.)
reactant + reactant  1 product
• Basically: A + B  AB
• Example: 2H2 + O2  2H2O
• Example: C + O2  CO2
DEMO: Write the reaction for the synthesis of MgO(s)
2 Mg(g)
+ O2(g) 
2 MgO(s)
Zn powder + Sulfur – See Hilt
2. Decomposition Reactions
• Decomposition reactions occur when a
compound breaks up into the elements or
in a few to simpler compounds
• 1 Reactant  Product + Product
• In general: AB  A + B
• Example: 2 H2O  2H2 + O2
• Example: 2 HgO  2Hg + O2
Elephant’s Toothpase
• Write the reaction for the decomposition
of hydrogen peroxide (H2O2)
2 H2O2

2H2O
Decompostion of KBrO3 – See Hilt
+
O2
Practice
• Predict the products. Then, write and
balance the following decomposition
reaction equations:
• Solid Lead (IV) oxide decomposes
PbO2(s) 
Pb + O2
• The formation of sulfur dioxide
S + O2  SO2
3. Combustion Reactions
• Combustion is actually an organic reaction
• Organic Compound + O2  CO2 + H2O
• Methane Mamba
CH4 + O2  CO2 + H2O
BELL RINGER
Write and balance the
following:
Decomposition of ammonia
Formation of calcium chloride
4. Single Replacement Reactions
• Single Replacement Reactions occur when
one element replaces another in a compound.
• A metal can replace a metal (+) OR
a nonmetal can replace a nonmetal (-).
• Must refer to Table J
• element + compound different element + different compound
A + BC  AC + B (if A is a metal) OR
A + BC  BA + C (if A is a nonmetal)
(remember the cation(+) always goes first!)
When H2O splits into ions, it splits into
H+ and OH- (not H+ and O-2 !!)
Practice
• Sodium chloride solid reacts with fluorine gas
2 NaCl(s) + F2(g) 2 NaF(s) + Cl2(g)
Aluminum metal reacts with aqueous copper (II) nitrate
2 Al(s) + 3 Cu(NO3)2 (aq)  3 Cu + 2 Al(NO3)3
5. Double Replacement Reactions
• Double Replacement Reactions occur
when a metal replaces a metal in a
compound and a nonmetal replaces a
nonmetal in a compound
• Compound + compound  product + product
• AB + CD  AD + CB
Double Replacement Reactions
• Mixed doubles in tennis, can the guy switch
with a girl?
• Example:
AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)
Double Replacement Reactions
• Lead (II) Nitrate and Potassium Iodide 
Lead (II) Iodide and Potassium Nitrate
Pb(NO3)2 + 2 KI 
PbI2 + 2 KNO3
BELL RINGER
Predict the following
products and ID the reaction
type:
MgCl2 + NaOH 
Practice
• Predict the product. Write and balance the
following synthesis reaction equations.
Aluminum metal reacts with
fluorine gas
2 Al(s) + 3 F2(g)  2 AlF3
You need to make sure your tray has:
1 Test tube rack
4 test tubes
Box of matches
10 ml Graduated cylinder
Watch glass
Test tube tongs
Crucible tongs
Scoopula
Wood splint
Plastic spatula
Microspatula
• Mole Calculations
•
1 – 45
2 – 46
3 – 47
4 – 48
5 – 49
6 – 50
7 – 51
8– 52
9– 53
10– 54
11– 55
12– 56
13– 57
14 – 58
15 – 59
16 – 60
17 – 61
18 – 62
19 – 63
20 – 64
21 – 65
22 – 66
23 – 67
24 – 68
25 – 69
26 – 70
27 – 71
BELL RINGER
Write and balance the
following:
Magnesium and oxygen
react to form magnesium
oxide.
HW Quiz
1.
2.
3.
4.
Decomposition of Aluminum oxide
Synthesis of sulfur trioxide
Combustion of Methane (CH4)
Sodium bromide and silver nitrate
form sodium nitrate and silver
bromide.
5. Balance the following:
C6H12O6  C2H5OH + CO2
Are you smarter than a
5th Grader ….
Lila decided to make more baked
goods for the bake sale. She used 1/8
lb less flour to make bread than to
make cookies. She used ¼ lb more
flour to make cookies than to make
brownies. If she used ½ lb of flour to
make the bread, how much flour did
she use to make the brownies?
Stoichiometry
A way to predict how many products can be made or how
many reactants would be needed. You need to get the
equation written correctly and balanced properly.
2H2 + O2  2H2O
For example:
You would need 2 moles of Hydrogen to make 2 moles of water
1 mole of oxygen would make 2 moles of water
If you made 6 moles of water, how much hydrogen would you need?
6 moles
What would the mass of that be?
 12 grams
If you had 12 moles of oxygen and 2 moles of hydrogen, how much
water could you make?
2 moles of water
Stoichiometry
How many moles of gold can be liberated from the
decomposition of 5.2 moles of gold (III) chloride?
2 AuCl3  2 Au + 3 Cl2
Mass
GFM
Moles
5.20 mol
Setup mole ratio
? 5.20 mol
m olesgiven m oleswanted

coeff .given coeff .unknown
5.20mol x

2
2
x  5.20mol
Stoichiometry
How many grams of Chlorine can be liberated from the
decomposition of 64.0g of gold(III) chloride?
2 AuCl3  2 Au + 3 Cl2
Mass
64.0g
GFM
303.5g/mol
71.0 g/mol
Moles
.211 mol
.317 mol
Setup mole ratio
?
22.5 g
m olesgiven m oleswanted

coeff .given coeff .unknown
.211mol x

2
3
x  .317 mol
Stoichiometry
How many grams of gold can be liberated from the
decomposition of 0.50 moles of gold (III) chloride?
2 AuCl3  2 Au + 3 Cl2
Mass
? 98.5 g
GFM
197.0 g/mol
Moles
0.50 mol
0.50 mol
Setup mole ratio
m olesgiven m oleswanted

coeff .given coeff .unknown
0.50 mol x

2
2
x  0.50 mol
BELL RINGER
How many grams is 1.25
moles of Sodium hydroxide
GFM = 40
Moles = 1.25 x 40 = 50 g
BELL RINGER
Gold (III) Chloride breaks
into its component elements.
Write the balanced equation
for this reaction.
BELL RINGER
Al + O2  Al2O3
What is the total number of
moles of O2 that must react
completely with 8.0 moles of
Al in order to form Al2O3?
Stoichiometry
How many moles of carbon dioxide are needed
to produce 0.333 moles of glucose in the
following reaction:
6 CO2 + 6 H2O 
C6H12O6 + 6 O2
Mass
GFM
Moles
2.00mol
?
Setup mole ratio
Don’t panic –
Balance the equation
0.333 mol
m olesgiven m oleswanted

coeff .given coeff .unknown
.333 mol x

1
6
x  2.00 mol
Stoichiometry
What mass of carbon dioxide is needed to react
with 54.0g of water in the following reaction:
6 CO2 + 6 H2O 
Mass
? 132.0 g
GFM
44.0 g/ mol
18.0g/mol
Moles
3.00 mol
3.00 mol
C6H12O6 + 6 O2
54.0g
Setup mole ratio
Don’t panic – Balance the equation
Must convert to moles – NEVER grams
m olesgiven m oleswanted

coeff .given coeff .unknown
3.0mol x

6
6
x  3.0mol
BELL RINGER
KClO3(s)  KCl(s) + O2(g)
If you have 20.0 g of potassium
chlorate, how many moles of
oxygen could you make?
Practice
Predict the products. Balance the equation
1. HCl(aq) + AgNO3(aq) 
HNO3(aq) +
2. 3 CaCl2(aq) + 2 Na3PO4(aq)  6 NaCl(aq) +
3. Pb(NO3)2(aq) + BaCl2(aq) 
AgCl(s)
Ca3(PO4)2(s)
PbCl2(s) + Ba(NO3)2(aq)
4. FeCl3(aq) + 3 NaOH(aq)  Fe(OH)3(s) + 3 NaCl(aq)
5. H2SO4(aq) + 2 NaOH(aq)  2 HOH + Na2SO4(aq)
6. 2 KOH(aq) + CuSO4(aq) 
K2SO4(aq) + Cu(OH)2(s)
BELL RINGER
Write the balanced equation
for the decomposition of
potassium chlorate.
BELL RINGER
If you wanted to make 200.0
moles of hydrogen gas from
the decomposition of water,
how many moles of water
would you need to start
with?
Mixed Practice
•
1.
2.
3.
4.
5.
State the type, predict the
products, and balance the following
reactions:
BaCl2 + H2SO4 
C6H12 + O2 
Zn + CuSO4 
Cs + Br2 
FeCO3 
To get Molecular Formula from
Empirical Formula
Problem: You know a compound has an empirical formula
of CN and a molecular mass of 52.0g. What is the
molecular formula?
• Find the mass of the empirical formula
C – 12
N – 14 = 26
•How many times does that mass divide into the molecular mass?
52 / 26 = 2
•Multiply that number to each element in the empirical formula
C2N2
Determining Formulas from %
Hydrated Crystals
A student starts with 25.0 g of Barium Chloride
Hydrate. The student performs the lab and has
21.4 g of anhydrous salt. What was the original
formula of the hydrated crystal?
1. You already have g so you do not have to assume 100.0 g.
2. Convert to moles
BaCl2  208.3 g/mol
Salt – 21.4 g ÷ 208.3 g/mol = 0.103 mol
H2O –
3.6 g ÷ 18.0 g/mol = 0.20 mol
Determining Formulas from %
Hydrated Crystals
Percent to mass
Mass to moles
Divide by small
Multiply ‘til whole
3. Divide by small
Salt  0.103 ÷ 0.103 = 1
H2O  0.20 ÷ 0.103 = 1.94
BaCl2• ?H2O
4. Multiply ‘til whole
Do Not need to here!
Just Round
BaCl2• 2H2O

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