Moles are a Chemist Best Friend
Chapter 10
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Objectives: Moles are a Chemist Best Friend
• I can identify what a mole is in chemistry.
• I can convert between moles and representative
particles of substances.
• I can convert between moles and mass of
substances.
• I can calculate the percentage composition of
substances.
Measuring Matter
What are three ways we can measure matter?
1.
2.
3.
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Measuring Apples
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Grouping Matter
• Easy way to measure all matter.
r500
Gross of pencils= 144
Dozen dougnuts= 12
Ream of paper = 500
Byte of information storage= 4 bits
Grouping Matter
• How do scientists’ group the representative
particles that make-up matter?
Representative particles: substances that make-up
matter.
Examples:
• Atoms
• Ionic Compounds
• Molecules (covalent cmpds.)
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Classification of Matter
Grouping Representative Particles
A mole is used to group representative particles.
1 mole = 6.02x1023 representative particles
(Avogadro’s Number)
•“The Mole is a Unit Song”
(nclark.net)
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Converting Moles to Representative Particles
Ex. Propane (C3H8) is a gas used for cooking and
heating. How many molecules of propane is equal
to 2.4 moles of propane?
Convesion: Representative Particles to Moles
Ex. Magnesium is a light metal used in the
manufacture of aircraft and automobile wheels.
How many moles of magnesium equals 1.25x1023
atoms of magnesium?
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Bell Ringer: Moles
1. Define and give two examples of a representative
particle.
2. a. What is a mole?
b. How many atoms are in a mole of Cu?
3. How many moles are in 4.65x1024 molecules of CO2 ?
Conversions: Mole-Representative Particles
(Homework Problems Key)
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
1.2x1024 molecules
9.0x1023 molecules
4.5x1023 molecules
9.0x1024 molecules
2.1x1023 molecules
1.00 moles
2.00 moles
2.5x10-4 moles
5.6x102 moles
1.2x10-4 moles
(2sig. Figs)
(2 sig figs)
(2 sig figs)
(2 sig figs)
(2 sig figs)
(3 sig figs)
(3 sig figs)
(2 sig figs)
(2 sig figs)
(2 sig figs)
Conversion: Mole-Representative Particles
Homework Problems
Converting Moles to Mass
• How do we convert from moles to mass?
Objectives: Moles are a Chemist Best Friend
• I can identify what a mole is in chemistry.
• I can convert between moles and representative
particles of substances.
• I can convert between moles and mass of
substances.
• I can calculate the percentage composition of
substances.
Mole-Mass Conversion
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Converting Moles to Mass
• How do we convert from the moles of a
substance to the mass of a substance?
Conversion: Moles- Mass
• Mole-Mass Conversion:
1 mole of a substance = molar mass of the substance
• Molar mass = substance’s atomic mass in grams
Molar Mass of an Element
• Molar mass = element’s atomic mass(grams)
• Round atomic mass to tenths place.
Ex. A mole of sulfur has a molar mass of?
Ex. A mole of sodium has a molar mass of?
Molar Mass of a Compound
• Molar mass = sum of the elements’ atomic masses
in the compound
• Need chemical formula to calculate the molar
mass of a compound.
Ex. A mole of NaCl has a molar mass of?
Ex. A mole of H2O has a molar mass of?
Bell Ringer: Chemistry
1. What is the representative particle for each substance
below? (atom, ionic compound, or molecule)
a. Na2O
b. Fe c. H2
d. Ne
2. How many atoms are in 2.5 moles of copper?
3. a. What is the molar mass of silver, Ag?
b. What is the molar mass of Al2(CO3)3?
Mole Packet Questions
Mole-Mass Conversions
• 1 mole = molar mass of substance
Ex. When iron is exposed to air, it corrodes to form
red-brown rust. How many moles of iron (III)
oxide are contained in 92.2g of pure Fe2O3?
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Mole-Mass Conversions
Ex. What is the mass of 9.45 moles of aluminum
oxide? (1 mole = molar mass of a substance)
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Mole Conversions
Mole to Particle Conversion:
1 mole = 6.02x1023 particles (atoms or cmpds)
Mole to Mass Conversion:
1 mole = molar mass of the substance (grams)
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Bubble Gum Lab
• Purpose: Practice mole conversions and
calculate the % composition of sugar in bubble
gum.
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Chemical Quantities Objectives (Chpt.10)
• I can identify what a mole is in chemistry.
• I can convert between moles and representative
particles of substances.
• I can convert between moles and mass of
substances.
• I can calculate the percentage composition of
substances.
Bell Ringer: Mole Conversions
1. Define “mole”.
2. Name the representative particle of each
substance. (atom, molecule, ionic compound)
a. oxygen gas
b. sodium sulfide
c. potassium
d. sulfur dioxide
3. What is the molar mass of a substance?
4. What is the conversion needed for each problem below?
a. mole to representative particle conversion?
b. mole to mass conversion?
Chemical Quantities Quiz Questions
Fun with Moles Review
Purpose: Work together in groups to
competitively review mole conversion
calculations learned before spring break.
Moles Conversion Review Worksheet
1. 0.407 moles
2. 1.8x1024 atoms
3. a. 40.3g b. 74g c. 78g
4. 0.0417 mole AgCl
5. 0.35 mole Cu(OH)2
6. 0.258 mol SiO2
7. 51 gH2O2
8. 120 g
9. 1,040 g C5H12
10. 52.7 g Cu
d.96 g
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Mole Conversions: 2 step problems
1. How many molecules are there in 100 grams of CCl4 ?
2. How many grams do 1.2x1021 molecules of BCl3 weigh?
Mole Conversions: 2 step Problems
Mole Conversion Lab
Problem: How many molecules are present in a
tablespoon of the following substances?
a. sodium chloride
b.water
c. calcium carbonate
Design and conduct an experiment that will help
you solve this problem. Make sure to include
a hypothesis, data section, and conclusion.
Mole Conversion Lab Questions
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Percentage Composition of a Compound
• Percent of mass each element contributes to the
compound’s molar mass.
• How do we calculate % composition of a
compound?
% Composition from Chemical Formula
% mass of element =
Ex. Propane, C3H8 is one of the compounds obtained from
petroleum and is used to fuel homes and gas grills.
Calculate the percent composition of propane.
% Composition of Compound
1. What is the % composition of each element in the
following compound, Al(NO2)3 ?
2. What is the mass of Al in 6.5 g of Al(NO2)3 ?
(Hint: use % composition data to solve problem)
Mole Conversions: 2 step Problems
Bell Ringer: Chemical Quantities
1. If a sample contains 2.34x1023 atoms of mercury,
how much does it weigh in grams?
% Composition as a Conversion Factor
% Composition as a Conversion Factor
•What is the mass of Al in 6.5 g of Al(NO2)3 ?
% Composition as a Conversion Factor
•What is the mass of N in 6.5 g of Al(NO2)3 ?
•What is the mass of O in 6.5 g of Al(NO2)3?
Bell Ringer: Chemical Quantities
1. How many grams are in 5.0 moles of Cs3N ?
2.How many moles are in 3.7x1021 cmpds. of NaCl?
3. What is the % composition of Cu2(SO4)?
4. How many grams of Cu are in 9.8 g of Cu2(SO4)?
Infinite Campus Update
• Mole Conversion Lab 10pts.
• Chemical Reaction Lab Rough Draft 20pts.
Formal Lab Reports: Final Copy
Computer Lab Days
Periods
Wed.
(4/25)
1st
Thurs.
(4/26)
Library
2nd
Library
Library
3rd
Rm 323
Rm 323
4th
Rm 323
6th
Library
7th
Fri.
(4/27)
Rm 323
Library
Library
Mon.
(4/30)
Library
Hydrate Lab
Hydrate Lab
• Hydrate: Cu(SO4)
.
H2O
• Anhydrous salt: Cu(SO4)
Mole Map
mass
molar mass
1mol
1mol
molar mass
moles
22.4L
1mol
1mol
6 .02 x 10 23 part icles
1mol
22.4L
6 .02 x 10 23 part icles
1mol
volume
at STP
number of
represent at ive
part icles
Objectives
• Chemical Quantities Test today.
• Hydrate Lab tomorrow-read procedures
• Bring Chemistry Textbook tomorrow
Chemical Quantities Test
• Choose one of the molar mass problems to
calculate.
• Test A and B qts10. calculate % composition
of C16H18N2O4S; omit qts. 12.
• Test C and D: qts 10 caculate % composition
of Fe(CH3O2)2; omit qts. 11