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Please refer to the list outside to find your
seat.
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When you turn in assignments, they go into the
tray on the back table.
Each tray corresponds to a different class period.
MAKE-UP WORK: If you are absent, you can find
the work you missed in the drawers next to the
recycle bin. They are labeled by day.
There is a separate drawer for Catalyst sheets.
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You can find any major event coming up on
the board below the Essential Question of the
day.
This may include upcoming quizzes, tests,
finals, projects, etc.
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You will receive a total of 4 hall passes and 2 late
homework passes for the semester.
You may not leave the room without a pass.
The late homework pass only works on
homework and does not excuse you from the
assignment. It allows you to turn it in after the
expiration date.
At the end of the semester, any unused passes
can be turned in for extra credit.

Catalysts
◦ Unit Conversions
◦ Pg. 234, #7-11
1/13/14 Moles and Molar Mass
 EQ: How are moles calculated?

1. How many atoms are present in one mole of
oxygen?
2. How many minutes are there in one year? Use
the t-chart to solve.

How many minutes are in 1 year?
1 year
365 days
24 hours
60 min
1 year
1 day
1 hour
525,600
1
525,600 min



1. Look up molar mass for each element.
2. Multiply by the number of atoms for each
element.
3. Add it together.
H2O: contains 2 hydrogen (H) and 1 oxygen (O)
H2 = 1.0 g/mol
x 2 = 2.0
O = 16.0 g/mol
X 1 = +16.0
18.0 g/mol
Molar mass of H2O = 18.0 g/mol
Ca3(PO4)2
Ca3 = 40.1 g/mol x 3 = 120.3
2 P = 31.0 g/mol x 2
= 62.0
2 O4 = 16.0 g/mol x 8 = 128.0
120.3+ 62.0 + 128.0 = 310.3 g/mol
Calculate molar mass of Pb(NO3)2. (#13)
Pb = 207.2 g/mol
x 1 = 207.2
N = 14.0 g/molx 2 = 28.0
O = 16.0 g/molx 6 = 96.0
Molar Mass = 331.2 g/mol



You will have 8 minutes to practice some
more.
Assignment: #1-15 odd
If you complete all 15 problems, you will
receive extra credit.

1 mole = molar mass of substance
◦ Ex: 1 mol Nitrogen = 14.0 g

When converting moles based upon the molar
mass, this is the equivalency that will go on
the right side of the t-chart.
96 g of phosphorous is how many
moles?
molar mass of P = 31.0 g/mol
96 g P
1 mol P
= 3.1 mol P
31.0 g P

1. Find the molar mass for potassium sulfide.
2. How many moles of potassium sulfide are in
45g?

K 2S =

 K2 = 39.0 g/mol x 2 = 78.0
 S = 32.0 g/mol = 32.0
 Molar Mass = 110.0 g/mol
45g K2S
1 mol K2S
110g K2S
0.41 mol


NaOH : 40g = 1 mol
How many grams of NaOH are there in 3
mol?
3 mol NaOH
40 g NaOH
1 mol NaOH
120 g NaOH

Complete the first four problems on the
Molar Mass Practice worksheet.

On the index card provided, solve the
following problem ALONE.
How many grams are in 100g of CaBr2?

Quiz on Thursday!
◦ Molar Mass
◦ Grams to moles/moles to grams conversion
◦ Particles to moles/moles to particles
1/14/14 Moles and Molar Mass
 EQ: How are moles calculated?

1. How many moles are in 100g of SO2?
2. How many grams are in 2.8mol of SO2?
1. How many moles are in 100g of SO2?
Molar Mass SO2: Sulfur = 32.0g/mol x 1 = 32.0
Oxygen = 16.0g/mol x 2 = 32.0
64.0g/mol
2. How many grams are in 2.8 mol of SO2?


1 mol = 6.02 x 1023 particles
How many atoms are there in 5 mols of
Carbon?
5 mol
6.02 x 1023 C atoms
1 mol
3.01 x 1024 C atoms


1 mol = 6.02 x 1023 particles
How many moles are there in 1.81 x 1024 C
atoms of Carbon?
1.81 x 1024 C atoms
1 mol
6.02 x 1023 C atoms
3.0 mol C


Complete #1-7 of particles to moles/moles
to particles practice
When you finish, begin working on the front
side of the molar mass worksheet labeled, “
Molar Mass Practice.”

On the index card provided, solve the
following problem ALONE.
1.How many moles are in 100g of
CaBr2?
How many formula units are in 5.0
mol of CaBr2?
2.

Quiz on Thursday (tomorrow)!
◦ Molar Mass
◦ Grams to moles/moles to grams conversion
◦ Particles to moles/moles to particles


1/15/14 Moles
EQ: How can I describe the amount of a substance in
mass, molecules, & moles?
Gimmie 5!
For each of the three words, write a definition
using no less and no more than 5 words for
each of them.
Mole (the chemistry kind!), Avagadro’s
number, and molar mass…look at notes or
book for help!
Ex: word is igloo: ice house where Eskimos abide
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

Going from grams to particles or particles to
grams involves a TWO-step t-chart.
How many atoms are present in 150g of SO2?
S = 32.0 g/mol x 1 = 32
O = 16.0 g/mol x 2 = 32 = 64 g/mol
150 g SO2
1 mol SO2
64 g SO2
6.02 x 1023 atoms SO2
1 mol SO2
=1.41 x 1024 atoms SO2

Convert the following masses to atoms.
◦ A. 25.8g of Hg
◦ B. 150g of Ar

Convert the following to grams.
◦ C. 4.22 x 1015 atoms U
◦ D. 1.25 x 1022 atoms O




A. 7.74 x 1022 atoms
B. 2.3 x 1024 atoms
C.
D. 0.332g

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

Instructions:
1. Weigh a piece of chalk.
2. Write your name on the
back of your paper.
3. Weigh the chalk again.
4. Chalk is calcium
carbonate. Determine the
number of moles that were
used to write your name.
SHOW ALL WORK!!
Moles of Chalk
Mass of chalk Initial: _____ g
Mass of chalk final: ______ g
Mass of chalk used: ______ g
Calculate the molar mass of CaCO3.
How many moles of chalk, CaCO3, did I
use to write my name?
How many molecules of chalk did I use to
write my name?

Work on the Molar Mass Practice worksheet
◦ You will get a homework stamp on this tomorrow.
1/16/14 Moles and Molar Mass
 EQ: How are moles calculated?

1.How many moles are in 75g of Li3N?
2. How many grams are in 3.0 mol of Li3N?
3. How many molecules are in 3.4 moles of KOH?
1.How many moles are in 75g of Li3N?
2. How many grams are in 3.0 mol of Li3N?
3. How many molecules are in 3.4 moles of KOH?

You will need something to write with and a
calculator.
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Look around the room. What percent of your
class is composed of girls? What percent is
composed of boys?
# of Girls =
# of Boys =
Total # =

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
Nigel goes shopping and spends $123 at three
different stores. He spends $42 at Best Buy, $13
at Target, and $68 at Foot Locker.
What percent of his money was spent at each
store?
Best Buy = $ 42 / $123 = 0.34 x 100 = 34%
Target = $13 / $123 = 0.11 x 100 = 11%
Foot Locker = $68 / $123 = 0.55 x 100 = 55%
100%
When showing the amounts of each element present
in a compound using percentage by mass
% mass =
grams of element
x 100%
total grams of compound
Part divided by total
Multiply by 100
Round till whole.
Please Make Rice!
Purple Monkeys Rule!
Px100
T
Percent Composition of CaCl2.
Ca = 40.1 g
Cl = 35.5 x 2 = 71.0 g
Total = 111.1 g
Ca = 40.1g/111.1 x 100 = 36%
Cl = 71.0g/111.1 x 100 = 64%
Exactly 9.63g of Mg combines with 3.48
g of Nitrogen.
9.63 g x 100 = 73% Magnesium
13. 11g
100% – 73% = 27% Nitrogen
(Or to check do 3.48/13.11 x 100)


Number 2
Exactly 29.0g of Argon combine with 4.30g
of Sulfur.
Numbers 3-6 on your Percent
Composition Practice worksheet.
 1/17/14


Empirical Formulas
EQ: What is an empirical formula?
Calculate the percent composition of each
element in Na2O.
 Na2O


= 2(23.0) + 16.0 =
46.0 + 16.0 = 62.0 g/mol
The formulas for compounds can be
expressed as an empirical formula and as a
molecular(true) formula.
Empirical
CH
CH
CO2
CH2O
Molecular (true) Name
C2H2
acetylene
C6H6
benzene
CO2
carbon dioxide
C5H10O5
ribose
46
Write your own one-sentence definition for
each of the following:
Empirical formula
Molecular formula
47

An empirical formula represents the simplest

The molecular formula is the true or actual
whole number ratio of the atoms in a
compound.
ratio of the atoms in a compound.
48
A. What is the empirical formula for C4H8?
1) C2H4
2) CH2
3) CH
B. What is the empirical formula for C8H14?
1) C4H7
2) C6H12
3) C8H14
C. What is a molecular formula for CH2O?
1) CH2O
2) C2H4O2
3) C3H6O3
49
Pretend that you have a 100 gram
sample of the compound.
Step 1: That is, change the % to grams.


Ex: Suppose a compound whose
molecular mass is 695g is analyzed to
contain 26.7% phosphorus, 12.1%
nitrogen, and 61.2% chlorine.

◦
◦
◦
Phosphorus = 26.7g
Nitrogen = 12.1g
Chlorine = 61.2g




Convert the grams to mols for each element.
26.7 g P 1 mol P
31.0 g P
12.1 g N 1 mol N
14.0 g N
61.2 g Cl 1 mol Cl
35.5 g Cl
= 0.862 mols P
= 0.864 mols N
= 1.726 mols Cl
Why do you need the number of moles of
each element in the compound?

Because!! Divide each number by the
least number of moles.

0.862 mols P/0.862mols = 1

0.864 mols N/0.862 mols = 1

1.726 mols Cl/0.862/mols = 2


Write the number of mols as a
subscript in a chemical formula.
Multiply the result to get rid of any
fractions.
P

= 1, N = 1, Cl = 2
Therefore the Empirical formula is
PNCl2
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


Step
Step
Step
Step
Step
1:
2:
3:
4:
5:
Change the % to grams.
Convert to mols.
Divide by the least number.
Write answer as a subscript.
Multiply if needed.

A compound is 43.64 % P and 56.36 % O.
What is the empirical formula?
1mol P
43.64 g P 
 1.4 mole P
31.0 g P
1 mol O
56.36 g O 
 3.5 mole O
16.0 g O
1.4 mol P
 1 mol P
1.4 mol



3.5 mol O
 2.5 mol O
1.4 mol
The ratio is P1O2.5
Get rid of decimals by multiplying to get a
whole number. Multiply by 2.
The empirical formula is P2O5.


Mole Test: Tuesday, Jan. 28
Mini Quiz Friday (one question for each of the
following)
◦ Percent composition, empirical formula, molar mass

Catalysts:
◦ Molar Mass Practice
◦ Mole Practice WS #2
◦ Mole/Particle Conversion WS
 1/22/14

Empirical Formulas
EQ: How do I calculate empirical and molecular
formulas?
 Calculate
the empirical formula of a
compound composed of 38.7% C, 16.2% H,
and 45.1% N.
1 mol C
38.7 g C 
 3.2 mole C
12.0 g C
1mol H
16.2 g H 
 16.2 mole H
1.0 g H
1mol N
45.1 g N 
 3.2 mole N
14.0 g N
3.2 mole C
 1 mol C
3.2 mol
16.2 mole H
 5 mol H
3.2 mol
3.2 mole N
 1 mol N
3.2 mol
The formula can also be written CH5N.
From empirical to molecular formula



The empirical is the formula with the lowest
whole number ratios between elements.
The molecular formula is a multiple of the
empirical formula. It represents the actual
molecule.
Examples:
CH3 is an empirical formula, C2H6 is a molecular
formula
(CH3 x 2 = C2H6)
CH2O is an empirical formula, C6H12O6 is a molecular
formula (CH2O x 6 = C6H12O6)


Since the empirical formula is the lowest
ratio, the actual molecule would weigh the
same or more.
Divide the actual molar mass by the molar
mass of the empirical formula to determine
the factor.
Step 1: Find the molar mass of the empirical
formula.
Step2: Divide the actual molar mass by the
molar mass of the empirical formula.
Step 3: Multiply the empirical formula
subscripts by your answer from step 2.


The empirical formula of a substance is CH5N.
The actual molar mass of the substance is 62
g/mol. What is its molecular formula?
CH5N = 12.0 + 5(1.0) + 14.0 = 31.0 g/mol
62.0 g/mol
2
31.0 g/mol


Multiply the empirical formula x 2.
The molecular formula is C2H10N2.

For Empirical Formula and molecular practice,
finish the worksheet provided to you
yesterday.