Ch 9 mole

Report
Ch 3.3 and Ch 9

Scientific Notation—great for very large or very
small numbers
Ex 1: Hope Diamond has
460,000,000,000,000,000,000,000 atoms
Ex 2: 1 Carbon atom of the Hope Diamond has a mass
of 0.00000000000000000000002 g
◦ 4.6 x 1023 atoms = Hope Diamond atoms (not 45 x
1022)
◦ 2 x 10-23 grams = carbon atom mass


4.6 and 2 are the coefficients of the number
The 10 to the raised power represents the
number of decimal places
1.
2.
3.
4.
5.
6.
3,000,000,000
4500
0.000023
438,000
0.00245
0.056
3x109
 4.5x103
 2.3x10-5
 4.38x105
 2.45x10-3
 5.6x10-2






(2.3 x 103)(8.2 x 104) =
(7.34 x 10-5)(8.221 x 10-2) =
9 x 106 ÷ 4.00 x 103 =
6.23 x 103 + 2.5 x 105 =
Think on this…do you need to write down
EVERY single number the calculator gives
you???
◦ Sig figs!

Meter for length

Second for time

Kilogram for mass (1 kg
= 2.2 lbs)

Mole for the amount of
substance
◦ Use a meterstick to
measure
◦ Weight is NOT the same
thing as mass!
◦ Use a scale to measure

Kelvin for temperature
◦ K = oC + 273
◦ 0 K = absolute zero
◦ Use a thermometer to
measure
◦ oC is another option, but
not Fahrenheit (in the
metric system)
◦ Use a stopwatch to
measure
◦ We will talk about mole
next chapter

Liter for volume

joule or calorie for
energy
◦ Use a graduated cylinder to
measure
◦ We don’t discuss this much
in this class…

Conversion factors
◦ Values can often be expressed in more than one
form
 $1 = 4 quarters = 10 dimes = 20 nickels = 100
pennies
 1 meter = 100cm = 1000mm = 0.001km
◦ equal values can be shown as a ratio equal to 1;
such ratios are called conversion factors…

$1
1000m
1km
60min
10 dim es
1hr
1km
1000m
conversion factors are useful for solving
problems in which given measurements
must be expressed in some other unit.



Dimensional Analysis: a way to problem
solve/calculate that uses conversion factors
to solve problems.
Calculate how many seconds old you are?
If you can run the 100 m dash in 12.72
seconds, how many kilometers per hour is
that?
Ex: Convert 1,000 kilometers into millimeters.
Ex: A boat is to be three hundred cubits long,
fifty cubits wide and thirty cubits high. How
big is that in feet?
◦ HINT: 1 cubit = 45 cm; 1 foot = 30 cm

How many minutes are there in one week?

How many seconds are in one year?

It takes 12 ounces of sugar to make 1 batch
of cookies. How many batches of cookies can
be made from a 5 pound bag of sugar?
Ch 3.3 and Ch 9

We live in a quantitative world…
◦
◦
◦
◦


How
How
How
How
much do you make?
old are you?
long is this class?
many questions are on the final exam?
How much? How many?
We measure by COUNT, MASS, and/or
VOLUME.





1 pair of shoes = 2 shoes
12 cupcakes =1 dozen cupcakes
1 reem of paper = 500 sheets
Each of these could be used as a conversion
factor
If there are 800 students at LACHSA, how
many dozen are there? Calculate it!
 MOLES
is a unit like these…it
represents a certain number!!
1
mole = 6.022 x 1023 of
anything

Moles are handy when there are large quantities
of matter.
◦ What if you needed to count the number of grains of
sand in 10 grams???

1 mole of apples =
602,200,000,000,000,000,000,000 apples
◦ Thank goodness for scientific notation! 


1 mole of $$ = $6.022 x 1023
1 mole of cheerios = 6.022 x 1023 cheerios
A mole is 6.02 x 1023 of anything!
A mole of basketballs would just about fit into a ball bag the
size of the Earth! So just how big is a mole?
Draw a 1 inch square box on your paper:
When the teacher says “go” put as many dots in that box as you
can in 30 seconds.
Now, count the dots. (A highlighter or differently-colored pen may be
useful.) x2, What is your dot making rate in dots/minute? _____________
Working at this rate, how many dots could you make in an hour?
_____________________
If a student can make 303 dots per minute, it will take 3.78 x 1015 years
to make a mole of dots!
Even if 25 students in the class worked at this rate, it would take the class
1.51 x 1014 years, making dots 24-7, to make a mole of dots!
6.022x1023 is referred to as Avogadro’s
Number
 1 mole of Fe atoms =
6.022 x 1023 atoms
 1 mole CO2 molecules=
6.022x1023 molecules
 1 mol NaCl molecules=
6.022x1023 molecules

Why the different units for
Fe vs. CO2 vs NaCl??





1 mole of carbon = 12.0 grams
1 mole of Fe = 55.9 g
1 mole of S = 32.1 g/mol
Look at a periodic table, where are these
numbers coming from?
for our purposes, we will round to 1 decimal place for each
atomic mass

Atomic mass= mass of 1 mole of the atom

Molar mass= atomic number = g/mol

Unit can be g or g/mol
1.
What is the mass of 1 mole of any element?
it’s atomic mass
2.
Where do you find it?
Periodic table…(decimal value)
3.
What is its unit of measurement?
Grams or grams/mol

To find the mass of 1 mole of a compound,
you must know the formula of the compound.
Molar masses of chemical compounds = the
sums of the molar masses of all the atoms in
one molecule of that compound.
Ex: calculate the molar mass of 1 mole of
carbon dioxide.

Calculate the mass of 1 mole of Sodium
Chloride (salt)
◦
◦
◦
◦
◦
◦
Gotta know the formula: NaCl
Na = 23.0 g x 1 atom in the compound = 23.0 g
Cl = 35.5 g x 1 atom in the compound = 35.5 g
Total = 23.0 + 35.5 = 58.5 g
The molar mass of NaCl = 58.5 g
1 mole of NaCl = 58.5 g
1.
Calculate the molar mass of water.
18.0 g/mol
2.
Calculate the mass of 1 mole of PCl3.
137.5 g/mol
3.
Calculate the molar mass of Zn(NO3)2.
189.4 g/mol
Pg 84
Mass
g
molar mass
1mole
1 mole
molar mass
Mole
1mol
_
6.022x1023 atoms
6.022x1023 atoms
1mole
# of
Particles
(atoms, molecules)
Use to convert between mole and mass and amount of particles
Pg 84
molar mass (g) = 1 mol
Mass
g
Mole
# of
Particles
1 mol = 6.022x1023
particles
(atoms, molecules)
Use to convert between mole and mass and amount of particles

When we convert moles to: molecules, atoms,
formula units, etc, we use the following conversion
factors:
23
1mol
1mol
23
6 . 02 x10 atoms
6 . 02 x10 atoms

How many molecules are in 2.00 moles of
sucrose?
2.00 moles x
23
6 . 02 x10 atoms
1mol
= 1.20x1024
molecules
23
1mol
1mol
23
6 . 02 x10 atoms
6 . 02 x10 atoms

How many moles are in 2.33 x 1024 molecules of
water?
3.87 moles

How many atoms are in 2.95 moles of Au?
1.77 x 1024
23
1mol
1mol
23
6 . 02 x10 atoms
6 . 02 x10 atoms





Warm up: Correct intro to mole worksheet
Correct HW
Practice gram to mole
Practice gram to particle
Chalk activity
Pg 84
molar mass (g) = 1 mol
Mass
g
Mole
# of
Particles
1 mol = 6.022x1023
particles
(atoms, molecules)
Use to convert between mole and mass and amount of particles

We use molar mass as a conversion factor:
molar mass
1mol
1mol
molar mass
Ex: grams to moles
 Calculate the number of moles in 75.0 g dinitrogen
trioxide.
Calculate the number of moles in 75.0 g dinitrogen
trioxide.
1. Find molar mass of N2O3
2. Use conversation factor

14.01x2 + 16.00x3 = 76.02g/mole
75.0g x
1 mole
76.02g
= .986mol N2O2


The molar mass can be used to convert
between mass and moles. Need to be able to
go both ways…from moles to mass or mass
to moles.
You need 3.0 moles of NaCl for a lab
experiment.
◦ How are you going to measure out 3.0 moles?
Can’t do it on a scale…
◦ You need to convert from moles to grams.
 In order to convert, you need to know the mass of 1
mole of NaCl

Now solve…
1.
Calculate the mass, in g, of 0.250 moles of
sodium chloride.
14.36 g
2.
Calculate the number of moles in 75.0 g of
nitrogen gas.

How much is ONE mole of
◦
◦
◦
◦
◦
◦
◦
◦
Zinc
Water (H2O)
NaCl
Chromium
Magnesium
Sodium Bicarbonate
Hydrogen peroxide
carbon




Mole song
Boseman:
https://www.youtube.com/watch?v=Pft2CASl
0M0
https://www.youtube.com/watch?v=xPdqEX_
WMjo
Pg 84
molar mass (g) = 1 mol
Mass
g
Mole
# of
Particles
1 mol = 6.022x1023
particles
(atoms, molecules)
Use to convert between mole and mass and amount of particles
1.
How many molecules are in 1.14 moles
of SO3?
(6.87 x 1023 atoms)
1.
Calculate the mass in grams of 2.50 moles
of Iron (II) Hydroxide. (Who remembers
how to write this formula???)
(225 grams)
3. If you have 7.31 grams of CuSO4, how
many moles is this?
◦ (0.0458 moles)
4. How many moles are in 4.65 x 1023
molecules of NO2
Is this a 1 step or 2 step problem???
(0.772 moles)
Pg 84
Mass
g
molar mass
1mole
1 mole
molar mass
Mole
1mol
_
6.022x1023 atoms
6.022x1023 atoms
1mole
# of
Particles
(atoms, molecules)
Use to convert between mole and mass and amount of particles
Pg 84
Mass
g
1 mol = molar mass
Mole
# of
Particles
1 mol = 6.022x1023
(atoms, molecules)
Use to convert between mole and mass and amount of particles
1. Find the mass, in grams of 4.52 x 1023
molecules of C20H42?
◦ (212 grams)
2. Find the number of atoms in 75.0 g of
dinitrogen trioxide?
◦ Molar mass = 76.0g/mol,
◦ 5.94x1023 atoms
3. How many grams are there in 2.80 x 1024
atoms of silicon?
◦ Don’t forget your sig.figs!
◦ 4.65x28.1g = 131g
4. How many grams is 2.7 x 1023 molecules of
Br2?
 71.6 = 72g
1.
How many molecules are in 1.14 moles
of SO3?
(6.87 x 1023 molecules)
2.
Calculate the mass in grams of 2.50 moles
of Iron (II) oxide.
179.8 g
3.
How many grams are there in 2.80 x 1024
atoms of N2?
◦ Don’t forget your sig.figs!
◦ 4.65x28.1g = 131g

Turn in warm ups and Mole worksheet!

How many moles are there in 2.80 x 1024 atoms
of silicon?
◦ Don’t forget your sig.figs!


How many moles is 2.7 x 1023 molecules of Br2?
NOTICE: how we calculated for atoms when
talking about an element and molecules
when talking about a compound?
◦ Can you calculate atoms for a compound? Could
you calculate atoms of Br2?
◦ YES, but that is not a single step problem…
◦ …see next slide 

Often multiple conversion factors are needed.
◦ Like if you need to convert your age to seconds…
◦ Go from years to months to days to hours to sec.
1. How many ATOMS of propane (a covlnt
cmpd!!) are in 2.12 moles of propane
(C3H8)?
◦ Why can you NOT go straight from moles to
atoms in this problem?
23
24 C H molecules
6.02x10
molecules
=
1.28x10
3 8
2.12 moles x
1mol
11 atoms per molecules
(1.28x1024) x 11 = 1.40 x1025 atoms
2.
How many ATOMS of Carbon are in 2.12
moles of propane (C3H8)?
23
24 C H molecules
6.02x10
molecules
=
1.28x10
3 8
2.12 moles x
1mol
11 atoms per molecules
3/11 of
atoms are C
(1.28x1024) x 11 = 1.40 x1025 atoms
3/11 (1.40 x1025 ) = 3.84 1024 C atoms
3. How many molecules are in 1.14 moles
of SO3?
(6.87 x 1023 molecules)
4. How many atoms are in 1.14 moles of
SO3?
(2.75 x 1024 atoms)
5. How many atoms are in 1.09 x 1024 molecules of water?
6. How many atoms of hydrogen in 2,560 atoms of water?
7. How many atoms of hydrogen in 1.50 moles of water?
1.
2.
3.
4.
What is the molar mass of 1 mole of
lithium?
What is the molar mass of 1 mole of carbon
dioxide?
What is molar mass of 35 grams of .5 mole
of aluminum?
What is the molar mass of 10 moles of
sodium that has a mass of 220 grams.
1.
2.
3.
4.
How many moles are in 32.58 g of H2O?
How many molecules are in 1.808 moles of
H2O?
How many atoms are in 1.09 x 1024
molecules of water?
What is the mass in grams of 7.23 x 1023
molecules of sucrose (C12H22O11)?
1.
2.
How many atoms of oxygen in 3.00 moles
of carbon dioxide?
How many atoms of hydrogen in 20.0
grams of H4CO
Volume (L)
22 . 4 L
1mol
1mol
22 . 4 L
The MOLE
1mol
1mol
molar mass
6 . 02 x10
6 . 02 x10
Mass (g)
23
1mol
molar mass
1mol
atoms
23
atoms
Molecules, atoms,
formula units
Volume L
1 mole
22.4 L
Mass
g
molar mass
1mole
1 mole
molar mass
Pg 84
22.4 L
1 mole
Mole
1mol
_
6.022x1023 atoms
6.022x1023 atoms
1mole
# of
Particles
(atoms, molecules)
Pg 84
Volume L
22.4 L = 1 mole
Mass
g
1 mol = molar mass
Mole
# of
Particles
1 mol = 6.022x1023
(atoms, molecules)

For gases, Avogadro (in 1811) proposed a
significant relationship that stated that: equal
volumes of gases at the same temperature and
pressure contain equal numbers of particles.
◦ Particle size varies for different gases but because particles
are so spread out, they do not take up any greater amount
of space.

Temp has an effect on volume
◦ As temp. increases, volume increases

Pressure also has an effect on volume
◦ As pressure increases, volume decreases

STP = Standard Temperature and Pressure
◦ Temp = 0 degrees C & pressure = 1 atm
MOLAR VOLUME = 22.4 L/mol
(the volume of one mole of a gas)

One mole of ANY gas will expand to have a volume
of 22.4 L at STP.

STP = Standard Temperature and Pressure
◦ Standard Temp: 0 degrees C
◦ Standard Pressure: 1 atm

The conversion factors (always):
22 . 4 L
1 mol
1 mol
22 . 4 L
1. How many moles of N2 are in 120 L of gas?
120L x
1mol
= 5.36 mol N2
22.4L
Can you then calculate the mass?
Pg 84
Volume L
22.4 L = 1 mole
Mass
g
1 mol = molar mass
Mole
# of
Particles
1 mol = 6.022x1023
(atoms, molecules)
2. What is the volume of 2.54 moles of methane gas?
◦ 56.9L
3. How many moles are in 6.00 L of H2 gas?
.268mol .3mol
4. How many grams are in 12 L of O2 gas?
17.1g= 17g
5. How many L of oxygen gas (at STP) are in 6.5 x 1024
molecules of oxygen gas?
242L = 240 L
Density= mass/ volume or D= g/L
6. The density of a gas at STP is 0.901 g/L.
What is the molar mass of the gas?
0.901 g x
L
22.4 L
1 mole
= 20.2 g/mol
7. What gas is it?
neon
8. What is the density of 1.00 mole of helium
gas?
4.00 g/mol x
1mol/22.4 L = .179 g/L


Follow the road map!
Moles  L or L moles: molar volume
22 . 4 L
1 mol

1 mol
22 . 4 L
Moles  g or g  moles: molar mass
molar mass
1mol
1mol
molar mass





0.6 moles of SO2 is produced when coal is
burned. How many liters of gas at STP is
this?
At STP, what volume does 1.25 moles of He
occupy?
74.5 liters of CO2 at STP is contained in a
flask. How many moles is this?
The density of a gas at STP is 1.964 g/L.
What is the molar mass of the gas?
What is the density of krypton gas at STP?
In your Chemistry Notebook, classwork sections:
Create your own molar road map including pictures
and conversation factors. Be creative and use color.
Include the following:
 Title
 Moles (in the middle)
 Particles
 Mass
 Volume
 Arrows between each unit (3 total)
 Conversion factors between each unit (3 total)
 A picture to represent each unit (4 total)
 Color for emphasis

End day
1.
2.
At STP, what volume does 1.75
moles of He occupy?
39.2L
What would be the volume of
8.00g of helium of STP?
44.8L
3.
What is the density of He at STP?
4.0g/mol x 1mol/22.4L = .179g/L

The recipe of chemistry


Suppose you are preparing a cake. Each Cake (Ck)
requires 1.0 cake mix (Cm), 0.5 cup of oil (Oi), 1.0
cup of water (Wa) and 2.0 eggs (Eg).
Write the balanced equation for making:
 1 ________ + 0.5 ________ + 1________ 2 _______ 1 ________
 1.0 cake mix + 0.5 cups oil + 1.0 cup water + 2 eggs  1.0 cake

How much is left over?
7
1
1.0 cake mix + 0.5 cups oil + 1.0 cup water + 2 eggs  1.0 cake

Calculate the number of cakes (Ck) that can be made
from 12 cake mixes (Cm)
◦ 12Cm x 1 Ck
1 Cm

= 12 Ck
Calculate the number of cakes (Ck) that can be made
from 10.0 cups of oil (Oi)
◦ 10.0 Oi x 1 Ck = 20 Ck
0.5Oi

If you need to make 29 cakes (Ck), how many eggs (Eg)
do you need?
◦ 29 Ck x 2 Eg
1 Ck
= 58 Eg
Stoichiometry: the calculation of quantities in chemical
reactions
 Equations
are a chemist’s recipe.
◦ Eqs tell chemists what amounts of
reactants to mix and what amounts of
products to expect.
 When
you know the
quantity of one
substance in a rxn,
you can calculate the
quantity of any other
substance consumed
or created in the rxn.
Nearly everything we use is manufactured from
chemicals.
◦ Soaps, shampoos, conditioners, CD’s,
cosmetics, medications, clothes.
 For a manufacturer to make a profit the
chemical processes carried out in industry
must be economical
 A balanced equation is needed
and used so chemicals are not
wasted when making products


How would you read:
◦ N2 (g) + H2 (g)  NH3 (g)

Balance and read:
◦ N2 (g) + 3H2 (g)  2NH3 (g)
◦ Coefficients can represent different possible units
 Atoms/molecules
 Moles
 Mass in grams
 Mass of reactants equals mass of products
 Law of Conservation of mass
 Liters (if compound is a gas at STP)
N2
+
3H2
1 mol N2
+
3 mol N2
28.0 g N2
22.
4L
22.4 L N2

2NH3

2 mol NH3
+ 3 (2.0 g H2)  2 (17.0 g NH3)
34.0 g
34.0 g

reactants
products
+
22.4
L
22.4
L
22.4
L
67.2 L H2


22.
4L
22.
4L
44.8 L NH3
◦ What are the possible mole ratios in:
N2 (g) + 3H2 (g)  2NH3 (g)
◦ 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of
NH3.
◦ Possible mole ratios for this formula:
1N2
3H2



1N2
2NH3
3H2
2NH3
Reaction to form ammonia in this 1:3:2 ratio.
Mole ratios are CONVERSION FACTORS!
Once you have the ratios, you can perform calcs. (a.k.a.
STOICHIOMETRY)
Amount
of given
(mol)
Mole ratio:
from balanced equation
Amount of
X Mole unknown =
Mole given
unkown
(mol)
Ex: How many moles of water are produced
from 5.80 moles of oxygen gas?
O2 + H2  H2O
O + 2H  2H O
1. Write equation
2. Balance!
3. Set up conversion factor
2
2
5.80mole O2 x
2
2 mol H2O
1 mol O2
11.6 moles water
1. How many moles of ammonia are produced from 0.60
moles of N2?
◦ (1.2 mol NH3)
2. How many moles of H2 are needed to react with 0.43
moles of N2 gas?
◦ (1.29 mol H2)
3. How many moles of H2 are needed to produce 1.98
moles of ammonia (NH3)?
◦ (2.97 mol H2)
Amount
of given
(mol)
Mole ratio:
from balanced equation
X Mole unknown =
Mole given
Amount of
unkown
(mol)
4. Ammonia, NH3 is a widely used fertilizer and used in
household cleaners. How many moles of ammonia are
produced when 6 mol of H gas react with excess
nitrogen gas?
4 mol NH3
5. The decomposition of potassium chlorate, KClO3 into
potassium chloride and oxygen gas is used as a source
of oxygen in the lab. How many moles of potassium
chlorate are needed to produce 15 mol of oxygen gas?
1. Write equation
2. Balance!
3. Set up conversion factor
10 mol KClO3
Historical Chemistry: pg 303, #1-2

End day
Sn + 2HF  SnF2 + H2
1.
How many moles of SnF2 will be
produced by 12.5 moles of HF?
1.
How many moles HF are needed to
produce 6.85 moles of SnF2?


No lab balance measures moles directly, instead grams is
a more practical unit.
To calculate grams:
1. convert to moles first, then grams
◦ Using our same example, you can calculate how many grams of
each compound:
N2 (g) + 3H2 (g)  2NH3 (g)
 REMEMBER: when you use a gram/mole conversion factor:
mol = molar mass
3.00 g N2 x
1 mol
28g
x
2 mol NH3
1 mol N2
x
17 g
1 mol
1
Particle A
Mass A
Volume A
6.022x1023
Molar
Mass
22.4 L
6.022x1023 Particle B
Mole
A
Mole
Ratio
Mole Molar
B Mass
22.4 L
Mass B
Volume B
Ex 1: What mass, in grams, of glucose is produced when
3.00 mol of water reacts with excess carbon dioxide to
produce glucose and oxygen?
6CO2 + 6H2O  C6H12O6 + 6O2
1. Write equation
1 mol glucose 180.2g
3.00mol
x
x
2. Balance!
6 mol water
1 mole
3. Set up conversation factor
90.1g glucose
Particle A
Mass A
Volume A
2.
6.022x1023
Molar
Mass
Mole
A
6.022x1023 Particle B
Mole
Ratio
22.4 L
Mole Molar
B Mass
Mass B
22.4 L
Volume B
What mass of carbon dioxide is needed to
react with 3.00 mol water?
132g CO2
6CO2 + 6H2O  C6H12O6 + 6O2
2. How many moles of H2O are formed from a
reaction using 824g NH3 is the reaction:
NH3 + O2  NO + H2O (unbalanced)
4NH3 + 5O2  4NO + 6H2O
72.5 mol H2O
Particle A
Mass A
Volume A
6.022x1023
6.022x1023 Particle B
Mole
A
Molar
Mass
Mole
Ratio
Mole Molar
B Mass
Mass B
22.4 L
22.4 L
Volume B
Ex 4: How many grams of SnF2 are produced from
the reaction of 30.00g HF with Sn.
Sn(s) + 2HF(g)  SnF2(s) +H2(g)
30.00g HF x
1 mol HF
20.0 g HF
x
1 mol SnF2
2 mol HF
x
156.7g SnF2
1 mol SnF2
117.5g SnF2
5. How many grams of NH4NO3 are required to produce
33.0g N2O? (the laughing gas needed for an anesthetic in dentistry)
60.0g NH4NO3
NH4NO3(s)  N2O(g) + 2H2O(l)
6. How many molecules of oxygen gas are produced when 29.2 g
of water is decomposed?
(4.88 * 1023 molecules
of O2)
1.
Carbon dioxide is produced from the synthesis of
oxygen gas with carbon monoxide. Write and balance
this chemical equation and then tell how many liters of
oxygen gas are required to burn 3.86 liters of carbon
monoxide. Assume STP.
◦ (1.93 L O2)
2. How many grams of NH4NO3 are required to produce
33.0g N2O? (the laughing gas needed for an anesthetic in dentistry)
60.0g NH4NO3
NH4NO3(s)  N2O(g) + 2H2O(l)
3. How much water in grams is produced in this
reaction?
27.0g H2O
Answer in classwork section of notebook:
N2 (g) + 3H2 (g)  2NH3 (g)
1. Calculate the number of grams of ammonia produced
by the reaction of 5.40 g of H2 with N2.
(30.6 g NH3)
2.
Calculate the number of liters of N2 needed in order
to react with 0.78 moles of H2.
(5.8 L N2)
3.
Calculate the grams of N2 needed in order to produce
9.23 x 1023 molecules of NH3.
(21.5 g N2)
Particle A
Mass A
Volume A
6.022x1023
Molar
Mass
22.4 L
Mole
A
6.022x1023 Particle B
Mole
Ratio
Mole Molar
B Mass
22.4 L
Mass B
Volume B
Answer in classwork section of notebook:
N2 (g) + 3H2 (g)  2NH3 (g)
1. Calculate the number of grams of ammonia produced
by the reaction of 5.40 g of H2 with N2.
(30.6 g NH3)
2.
Calculate the number of liters of N2 needed in order
to react with 0.78 moles of H2.
(5.82 L N2)
3.
Calculate the grams of N2 needed in order to produce
9.23 x 1023 molecules of NH3.
◦ (21.5 g N2)
Ch 9.2: Answer #2-4 on page 311

You will ALWAYS use the new MOLE-MOLE ratio step to
get you from where you are to where you are are going.
Particle A
Mass A
Volume A
6.022x1023
Molar
Mass
22.4 L
Mole
A
6.022x1023 Particle B
Mole
Ratio
Mole Molar
B Mass
22.4 L
Mass B
Volume B

Carbon dioxide is produced from the synthesis of
oxygen gas with carbon monoxide. Write and balance
this chemical equation and then tell how many liters of
oxygen gas are required to burn 3.86 liters of carbon
monoxide. Assume STP.
◦ (1.93 L O2)

Aluminum reacts with oxygen to produce Aluminum
Oxide. How many moles of aluminum are needed to
form 3.7 moles of Aluminum Oxide? Write the
balanced equation and solve.
◦ (7.4 mol Al)

How many molecules of oxygen gas are produced when
29.2 g of water is decomposed? The balanced chemical
equation is given for you. Use your new mole map to
solve.
2H2O –electricity 2H2 + O2
◦ (4.88 * 1023 molecules of O2)

How many molecules of oxygen are produced by the
decomposition of 6.54 g of Potassium Chlorate? The
balanced chemical equation is given for you. Use your
new mole map to solve.
2KClO3  2KCl + 3O2
◦ (4.82 * 1022 molecules of O2)

Sodium hydroxide reacts with Sulfuric acid to produce
water and Sodium Sulfate. Calculate the amount of water
(in grams) that would be produced from 40.87 g of the
acid.
◦ (15.0 g H2O)

In a combustion reaction, C2H4 reacts with oxygen to
produce H2O and CO2 in the following reaction. Balance it
and then determine the amount of oxygen (in grams) that
is consumed if 2.69g of water is produced.
◦ _____C2H4 + _____O2  _____CO2 + _____H2O
 (7.17 g O2)
Mole ratio:
(balanced equation)
Molar mas:
(periodic table)
Amount
X Mole unknown x molar mass unknown(g)
of given
Mole given
1 mole unkown
=
(mol)
Molar mas:
(periodic table)
Mass of
X 1 mole given x
given (g) molar mass
= given (g)
mass of
unkown
(g)
Mole ratio:
(balanced equation)
mol unknown
mol given
Amount
unkown
(mol)
Mass of
given
(g)
1 mole given
mol unknown
X molar mass x mol given X
= given (g)
mole mass
1 mol
unknown
mass of
unknown
(g)

End day
Carbon dioxide is produced from the synthesis of
oxygen gas with carbon monoxide. Write and
balance this chemical equation and then tell how
many liters of oxygen gas are required to burn 3.86
liters of carbon monoxide. Assume STP.
1.
◦ (1.93 L O2)
Particle A
Mass A
Volume A
6.022x1023
6.022x1023 Particle B
Molar Mass Mole
A
22.4 L
Mole
Ratio
Mole Molar Mass Mass B
B
22.4 L
Volume B

The difference in the optimal, expected
outcome and the actual tested outcome
• Experimentation is
not perfect
• Not all reactant are
react so some may
be left over
• Conditions may
not be perfect for a
full reaction

Limiting reagent: reactant that determines the
amount of product that can be produced.
◦ It limited…


Excess reagent: reactant that is not used up in the
reaction - there is more available than needed
Steps to determine LR
 Calculate theoretical yield (g or mol)
 Determine limited reagent
 Use the original actual yield of the limiting reactant to calculate
product produced (in moles or grams)
Flask
1
2
3
4
5
6
Volume
acetic
acid
(mL)
25ml
25ml
25ml
25ml
25ml
25ml
Sodium 0.50g
bicarbon
ate (g)
1.00g
1.50g
2.00g
2.50g
3.00g
Which system will produce the most CO2 product?
Ex 1. Given the following balanced equation, determine which is
the LR if 2.70 moles of C2H4 is reacted with 6.30 moles of O2.

C2H4 + 3O2  2H2O + 2CO2
◦ (O2 is LR)
2.70 mol C2H4 x 2 mole H2O = 5.4 mol H2O
1 mole C2H4
6.30 mol O2 x
2 mole H2O = 4.20 mol H O
2
3 mole O2
Less= limiting reagent=O2
2. Using the info gathered from above, calculate the GRAMS of
water that will be produced.
4.20mol x 18g/mol =
75.6 g H2O
3. Identify the LR when 6.00 g HCl reacts with 5.00
g Mg in the following reaction:
 Mg + 2HCl  MgCl2 + H2
 (HCl is LR)
4. Using the info gathered from above, calculate the
GRAMS of hydrogen gas that will be produced.
◦ (0.164 g H2)




% yield = ____actual yield___ x 100
theoretical yield
measure of the efficiency of a reaction carried out in
lab.
Actual yield would be given in problem or determined
from actually performing the lab.
Theoretical yield can be calculated using the Limiting
Reagent.

If 15.0 g of nitrogen gas reacts with 15.0 g of hydrogen
gas, 10.5 g of ammonia (NH3) is produced. Calculate
the percent yield.
◦
◦
◦
◦
◦
N2 yields 1.07 mol NH2
H2 yields 5.0mol NH2
Limiting reactant: N2
(theoretical yield: 18.2 g NH3)
(percent yield: 57.7%)
1. Balance chemical equation
2. Find limiting reactant
3. Calculate theoretical yield
4. Find percent yield
% yield = ____actual yield___ x 100
theoretical yield



Calculate the number of moles in 9.023 x
1023 molecules of NO2. (6.48 moles)
Calculate the volume of 2.30 moles of SO2
gas at STP. (51.5 L)
Find the molar mass of B2(SO3)3.
261.9
g/mol




HS-PS1-7. Use mathematical representations to support the
claim that atoms, and therefore mass, are conserved during
a chemical reaction.
HS-PS1-6. Refine the design of a chemical system by
specifying a change in conditions that would produce
increased amounts of products at equilibrium.
HS-PS1-5. Apply scientific principles and evidence to provide
an explanation about the effects of changing the
temperature or concentration of the reacting particles on the
rate at which a reaction occurs.
HS-PS1-3. Plan and conduct an investigation to gather
evidence to compare the structure of substances at the bulk
scale to infer the strength of electrical forces between
particles.

HS-PS1-7.
Use mathematical
representations to support the claim that
atoms, and therefore mass, are conserved
during a chemical reaction.
CA State Standards
 D2. Investigate quantitative relationships in chemical
reactions, and solve related problems;
 D3. Demonstrate an understanding of the mole
concept and its significance to the quantitative
analysis of chemical reactions.

HS-PS1-6.
Refine the design of a
chemical system by specifying a change in
conditions that would produce increased
amounts of products at equilibrium.

HS-PS1-5. Apply scientific principles
and evidence to provide an
explanation about the effects of
changing the temperature or
concentration of the reacting particles
on the rate at which a reaction occurs.

HS-PS1-3. Plan and conduct an
investigation to gather evidence to
compare the structure of substances
at the bulk scale to infer the strength
of electrical forces between particles.

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