Transcript Notes

If I had a million
dollars…
Song
If I had a million dollars…
You are an incredibly valuable student and I want to reward
you. You have 2 options for receiving your reward:
Option 1: You can either come to school for 10 days straight
and receive one million dollars (regular 7 hour school day)
or
Option 2: You can earn a dollar per second up to one million
dollars.
You would like to buy an elite condo in the Bahamas that costs
exactly one million dollars. Which deal will allow you to
purchase the condo first?
How many Apple Jacks are in
the container? (NO counting!)
 On your white boards, you and your partner
will develop a procedure for determining the
number of Apple Jacks in the container
 You have a smaller container and scale for
reference
 The mass of the apple jacks = 230.1g
Data – your estimate
Data – the actual quantity!
 There are 682 apple jacks in the large
container!
BRN – fill in the blanks #1-5
 When you buy eggs you usually ask for a (1)____________ eggs.
You know that one dozen of any item is (2)_________.
 Paper is not packaged by the dozen, it is packaged by the
ream. A ream of paper has 500 sheets. Why is it useful to use
units like a dozen or a ream? (3) ________________________
 What determines how many items should make up a particular
unit? (4) ___________________________________________
 If you were asked to design a new unit to count something,
what would you consider when choosing how many items
should be included in your new counting unit?
(5) _______________________________________
When given the number of
KNIGHTS…
_________________________________ by a
KNIGHT to find the number of items
When given the number of
items…
________________________________ by a
KNIGHT to find the number of KNIGHTS
The mole…
 One MOLE of anything has
602,200,000,000,000,000,000,000 items.
 This number is called AVOGADRO’S NUMBER
and is usually written in scientific notation as
6.022 x 1023
 One MOLE of anything has 6.022 x 1023 items
The mole
When given the number of moles, we
______________________ by Avogadro’s
number to find the number of items
When given the number of items, we
_______________________ by Avogadro’s
number to find the number of moles
Closure
Here’s How: How do we determine the
number of moles when given the
number of particles?
Mole Notes
Dimensional Analysis
 The factor-label method was developed to
keep track of units in multi-step conversion
problems (also known as dimensional analysis).
 In the method, equalities (i.e., conversion factors) are
set up in fraction form. The equalities are then lined
up sequentially and units used on the top and
bottom of neighboring fractions are alternated so
that units cancel.
 Crash Course
Dimensional Analysis
 For example, consider the conversion of inches
to centimeters (1.00 in = 2.54 cm).
How many centimeters are in 5.00 inches?
Conversion Factors
= Sign
The word per
The word for
The word in
Dimensional Analysis
Dimensional Analysis
1. Determine what the question is asking you to
solve for.
2. Determine what is given in the problem to be
converted.
3. Identify and plug in the appropriate conversion
factors as fractions (what is on top must also be
on bottom).
4. Cancel units
5. Verify your answer. (Units must match units in
step 1. If the answer doesn’t match, repeat 3
and 5).
Self-Motivated Practice
• For the next few months, we will be doing a lot of
math and calculations.
Self-Motivated Practice
 YOU WILL NEED A CALCULATOR EVERY DAY!!!
Self-Motivated Practice
 The correct answer on these quizzes are worth
very little.
 Therefore you will not get any credit (0/10) if
you do not show your work (Factor- Labeling).
 Let me repeat this: A quiz with the correct
answer but no work shown will get a score of
(0/10).
 Show and write out the work!
The MOLE
 KC 1: The mole (mol) is an SI base unit used to
measure the amount of a substance.
 KC 2: 1 mole is equal to the number 6.02 x 1023
particles.
 KC 3: Avogadro’s number is another name for the
value of one mole, 6.02 x 1023.
 mole video
Avogadro
 In 1811 Avogadro hypothesized that equal
volumes of gases at the same temperature
and pressure contain equal numbers of
molecules
 Determining the number:
 If you divide the charge on a mole of electrons by
the charge on a single electron you obtain a value of
Avogadro’s number of 6.02214154 x 1023 particles per
mole.
Counting Particles
There are three types of representative
particle; atom, molecule, and formula
units.
The unit atom is used with single element.
The unit molecule is used with covalently
bonded element (2 non-metals).
The unit formula units are used with ionicly
bonded elements (1 metal and 1 nonmetal).
Practice
 KC 4: How many formula units of NaCl (sodium
chloride) are in 43.4 moles?
Practice
 KC 5: How many moles of copper are there in
1.54 x 1023 atoms of Cu?
Practice
 KC 6: Calculate the number of particles in 2.15
moles of iron.
How big is a mole?
 1 Mole of marbles would fill the entire Grand
Canyon and there would still be enough left over
to displace all the water in Lake Michigan and a
few other lakes!
 Computers can count at the rate of over 800
million counts per second. At this rate it would
take a computer over 25 million years to count to
6.02 x 1023
How big is a mole?
 A mole of hockey pucks would be equal to the
mass of the Moon.
 Assuming that each human being has 60 trillion
body cells (6.0 x 1013) and the Earth's
population is 6 billion (6 x 109), the total number
of living human body cells on the Earth at the
present time is 3.6 x 1023 or a little over half of a
mole.
Mass of a mole
 What does 1 Knight of skittles and 1 Knight of
sprees have in common?
 What is different about a Knight of skittles and
sprees?
 What does 1 mole of copper and 1 mole of
carbon have in common?
 What is different about 1 mole of copper and 1
mole of carbon?
Think-Pair-Share WHY?
Mass of a mole
Chemical
Formula
Moles of
Sample
Mass of
Sample
Al
1 mol
26.982g
NaCl
1 mol
58.443g
MgO
1 mol
40.304g
MgSO4
1 mol
120.366g
Molecular
Mass
Mass of a mole
 1 mol of copper and 1 mol of carbon have
different masses because they have different
numbers of protons, neutrons, & electrons
Mass of a mole
 Key Concept 7: A mole always contains the
same number of particles; however, moles of
different substances have different masses.
Chemical Formulas and the Mole
 Chemical formulas indicate the numbers and types of
atoms contained in one unit of the compound
 One dozen molecules of CCl2F2 contains 12 C atoms,
2(12) Cl atoms, and 2(12) F atoms.
 Similarly, one mole of CCl2F2 contains one mole of C
atoms, two moles of Cl atoms, and two moles of F atoms
Mass of a mole
 Key Concept 8 - Molecular Mass: (atomic
mass, formula mass) of a molecule is its
average mass as calculated by adding
together the atomic weights of the atoms in
the formula.
MM QT
MM= Molecular Mass
Q= quantity
T= Total
MMQT - NaOH
MM
Na
O
H
Total =
Q
T
Mass of a mole
 Key Concept 9 - Molar mass is the mass in
grams of one mole of any pure substance.
 Key Concept 10 - The molar mass of any
element is numerically equivalent to its
molecular mass (atomic mass, formula mass)
and has the units g/mol
CONVERSION FACTOR ALERT
Mass of a mole
 Key Concept 11: What is the molar mass of the
following compounds?
 Potassium sulfate
 (NH4)2CO3
Converting using moles
 Conversion factors so far…
Converting using moles
 Key Concept 12: How many grams of zinc are there in
1.5 moles of Zn?
 Key Concept 13: How many molecules of carbon
dioxide are there 4.0g of carbon dioxide?
Converting using moles
 Key Concept 14: Gold (Au) is one of a group of
metals called coinage metals (copper, silver,
and gold). How many atoms of gold are in a
U.S. Eagle, a gold bullion coin with a mass of
31.1g Au?
Converting using moles
 Key Concept 15: The characteristic odor of
garlic is due to allyl sulfate [(C3H5)2S]. What is
the mass of 2.50 mol of (C3H5)2S ?
Converting using moles
 Key Concept 16: Aluminum chloride (AlCl3) is
used in refining petroleum and manufacturing
rubber and lubricants. A sample of aluminum
chloride has a mass of 35.6g. How many
formula units are present?
Percent Composition of an Oreo
 Obtain an Oreo. The cookie is made up of
WAFER and CREAMY FILLING.
 Using a balance, a plastic knife and a napkin
(to keep the cookie from directly touching the
balance), calculate the percent of the cookie
that is made up of each part.
 You have 15 minutes to complete and be
ready to explain the process and your answer
Percent Composition of a
Compound
 KC 17: Mass percent composition – percent of
total mass of a substance contributed by each
element in the substance
 Found from comparing the mass of each
element to the total mass of the substance
Percent Composition
 KC 18: Calculate the percent composition of
water (H2O)
Percent Composition
 KC 19: Calculate the mass percent of oxygen
in sodium sulfate.
Percent Composition
 KC 20: Calculate the percent composition of
nitrogen in calcium nitrate
Empirical vs. Molecular Formula
 KC 21: Molecular formula – formula of the
molecule as found in nature
 KC 22: Empirical formula – simplest ratio of
atoms in a molecule
 Example –
C6H12O6
vs.
CH2O
Empirical vs. Molecular Formula
 Circle the compounds that are given as
empirical formulas:
 CaO
 Mg2(SO4)2
 Be2S2
 LiCl
 C6H12O6
Formula Mass vs. Molecular Mass
 The formula mass (formula weight) of a molecule is the sum
of the atomic weights of the atoms in its empirical formula
 KC 23: Formula mass = empirical formula
 The molecular mass (molecular weight) of a molecule is its
average mass as calculated by adding together the
atomic weights of the atoms in the molecular formula
 KC 24: Molecular mass = molecular formula
 Example –
C6H12O6
180 g/mol
vs.
CH2O
30 g/mol
Percent Composition and
Empirical Formula
 KC 25:
1. Assume 100g of the sample. Use the percentages as
your grams
2. Convert the grams to moles for each element
3. Divide each of the moles by the lowest number of
moles present to get a whole number
4. Round the number of moles as necessary or multiply
each mole number by a fraction to get a whole
number
5. Use the whole numbers to write the empirical formula
Percent Composition and
Empirical Formula
 Given data on percent composition of a
compound, you can find the empirical formula
 Example – Lactic acid is 40% carbon, 6.71%
hydrogen, and 53.3% oxygen by mass.
Calculate the empirical formula.
Percent Composition and
Molecular Formula
 To determine the molecular formula from the
empirical formula you need the molar mass
 KC 26:
molar mass given in problem
= whole
molar mass of empirical formula found
number
 Example – Lactic acid has a molar mass of
90.08g/mol. Determine its molecular formula.
Practice
 KC 27: A compound is found to have 9.2%
boron and 90.8% chlorine. Determine the
empirical formula
Practice
 KC 28: A compound is shown to contain 50.1%
sulfur and 49.9% oxygen. The molar mass of the
compound is 128 g/mol. Determine the
compound’s molecular formula.