CHEMISTRY 11
CHAPTER 6
INTERACTIVE LESSON
TEACHER’S
NOTES
FOR THE TEACHER
Lesson Objectives
• Review, reinforce, and extend the concepts in Chapter 6: Quantities in
Chemical Formulas.
• This lesson relates to expectations D2.1, D2.3, D2.4, D3.1, D3.2, and D3.3.
Lesson Notes
Slide 6
• As a prompt to the first task, ask students to think about the consequences
of excess sodium in terms of the given phrases. With the second task, the
key point is that the average sodium level is above not only the
recommended level, but also the maximum tolerance.
Slides 12 – 15
• This calculation extends the process students followed in slides 9 and 10.
They use the compound amount to determine, first, the number of formula
units, and then the number of individual ions. Discuss the steps in the whole
process with students, in terms of how each step leads logically to the next.
FOR THE TEACHER
Lesson Notes
Slide 16
• Suggest to students that more than one thing is changing during the
animation. [mass, number of molecules, number of atoms]
Slides 19 and 20
• For slide 20, prompt students to think about which element they will use as
the base of the ratio, and why.
Slides 24
• The discussion question encourages students to think about how variables
such as the type of paper might affect the outcome of an investigation.
Slides 25
• Prompt the students to think about where they would begin in the sequence,
and where they need to end. Also, which steps must logically follow other
steps?
Diabetes: Diagnosis and Management
Section 6.1
Diabetes is usually diagnosed by tests that reveal excess glucose
in a patient’s blood. Diabetes can be managed, often by diet alone,
reducing blood glucose back toward normal levels and helping
patients lead healthy lives. Match the correct type of analysis to
each blood glucose test apparatus.
qualitative
quantitative
Discussion: Diabetes: Diagnosis and
Management
Section 6.1
Discuss why a quantitative instrument would be better suited to
diabetes management than would a qualitative one.
Sodium Ions: Too much of a Good Thing?
Section 6.2
1. Complete the following statements using the words or phrases
below.
water
blood pressure
fluid levels
Sodium ions are needed to help regulate __________ in the
body.
Excess sodium ions make the body retain __________, which
raises __________.
2. Match each quantity of sodium with Health Canada’s description.
1500 mg
●
●average Canadian intake
2300 mg
●
●recommended daily intake
3400 mg
●
●maximum tolerable limit
Discussion: Sodium: Too Much of a Good
Thing?
Section 6.2
Excess sodium creates health risks for human beings. Why can we
not just eliminate sodium from our food?
Section 6.3
What’s in a Mole?
Complete each statement by filling in the blank space(s).
•
•
•
A mole of __________ has a mass of
exactly 12 g.
In chemistry, an entity could be an
__________, __________, __________,
or __________.
When measured, 1-mol samples of sucrose,
sodium chloride, and carbon have different
__________ and volumes, but the same
number of __________, 6.02 × 10
.
Click the screen for a note:
Avogadro’s Constant is 6.02 × 1023.
sucrose
sodium
chloride
carbon
Calculating Amount from Mass
Section 6.4
A portion of French fries contains 1.15 g of sodium chloride, NaCl.
Calculate the amount of sodium chloride in 1.15 g. Use the given
data to complete the calculation.
g
g
; MCl = 35.45
mol
mol
Required: amount of sodium chloride, nNaCl
Given: mNaCl = 1.15 g; Mna = 22.99
Solution:
Step 1: Calculate to molar mass of sodium chloride, MNaCl.
MNaCl = 1(MNa) + 1(MCl)
= __________ + __________
g
MNaCl = __________ mol
Step 2
Calculating Amount from Mass
Section 6.4
Step 2: Multiply the mass of sodium chloride by a conversion
factor of
1 mol
.
g
nNaCl =
g×
nNaCl =
mol
1 mol
g
Statement: There are
sample.
of sodium chloride in a 1.15 g
Discussion: Calculating Amount from Mass
Section 6.4
How would your solution method change if you were calculating the
amount of calcium chloride in a 1.15 g sample?
Calculating the Number of Ions in a Sample
Section 6.5
Determine the number of calcium and chloride ions in a 32.5 g
sample of calcium chloride. Use the given data to complete the
calculation.
Given: m
= 32.5 g ; MCa = 40.08
Ca2
Cl
g
g
; MCl = 35.45
mol
mol
Required: number of calcium and chloride ions, N Ca2+ and NClSolution:
Step 1: Calculate the molar mass of calcium chloride, M
.
Ca Cl
2
= 1(MCa) + 2(MCl)
M
Ca2
Cl
=
+ 2(
g
M
Ca2
Cl= __________ mol
)
Step 2
Calculating the Number of Ions in a Sample
Section 6.5
Step 2: Calculate the amount of calcium chloride using an
appropriate conversion factor.
1 mol
nC aC
= __________ g ×
2 l
g
nC aC
= __________ mol [carry five decimals]
2 l
Step 3
Calculating the Number of Ions in a Sample
Section 6.5
Step 3: Calculate the number of formula units in the 32.5 g sample.
formula units
= (__________ mol ) (
)
nC aC
2 l
1 mol
nC aC
= __________ formula units [carry four decimals]
2 l
Step 4
Calculating the Number of Ions in a Sample
Section 6.5
Step 4: Determine the number of each type of ion present.
NCa2+ = ( __________ formula units) ( 1 calcium ion
)
1 formula unit
NCa2+ = __________ ions
NCl- = ( __________ formula units) ( 2 chloride ions
1 formula unit
NCl- = __________ ions
)
Statement: A 32.5 g sample of calcium chloride contains
__________ calcium ions and __________ chloride ions.
The Law of Definite Proportions
Section 6.6
Imagine water
molecules being put
one by one into each
side of this scale. Click
the image on the right
to play the animation.
What is the difference between the two sides of the
scale? What is the same?
The Law of Definite Proportions
Section 6.6
Complete the definition below. Click the screen to reveal the
answers.
Law of Definite Proportions: the statement that a compound
always contains the same ___________
proportion of ___________
elements by
___________
.
mass
Discussion: The Law of Definite Proportions
Section 6.6
How could the law of definite proportions help you to determine a
chemical formula from lab data that gave you the ratio of elements in
a substance?
Determining an Empirical Formula
Section 6.7
Determine the empirical formula of a compound that contains 56.0%
vanadium and 44.0% oxygen. Use the data from the problem to
complete the calculation for Step 1.
Given: % V = 56.0 %; % O = 44.0 %; MV = 50.94 g/mol; MO = 16.00 g/mol
Required: empirical formula of the unknown compound, VxOy
Solution Step 1: A 100.0 g sample of this compound contains
g
of vanadium and __________ g of oxygen. Calculate the amount of each
element in the 100.0 g sample.
nV = (
g)(
1 mol
)
nV = __________ mol [carry four decimals]
nO = (
g)(
1 mol
)
nO = __________ mol [carry four decimals]
Step 2
Determining an Empirical Formula
Section 6.7
Step 2: Divide the amount of each element by the smallest amount.
n
n
=
=1
=
= __________
n
n
Assign
a value of
, relative to
.
Step 3
Determining an Empirical Formula
Section 6.7
Step 3: These calculations give an empirical formula of V1O
Multiplying both subscripts by
gives V O .
.
Statement: The empirical formula for the compound is
.
Chemical Fingerprinting
Section 6.8
A mass spectrometer measures the masses of ionized entities by
measuring their deflection as they pass through a strong magnetic
field. Match the correct tag to each part of the diagram or to the graph.
analyzer
Note
detector
mass
ion
spectrum source
Note: Chemical Fingerprinting
Section 6.8
The fragment pattern produced is often unique to a
substance, and can be used to identify it.
Discussion: Chemical Fingerprinting
Section 6.8
If Canadian scientists wanted to test Canadian currency in a similar
procedure to the British, what variable would they have to change?
Why?
Determining a Molecular Formula
Section 6.9
When you are given percentage composition data for a molecular
compound and its molar mass, there are several steps needed to
determine the molecular formula for the compound. Rearrange these
steps in the correct order. Click the screen for a hint. Then click the
screen again to reveal the answers.
6
2
5
1
3
4
Determine the molecular formula.
Determine the simplest ratio for the elements. (Step 2)
(Step 5)
Solve for the mass multiple.
Determine the amount of each element in a 100.0 g sample.
Determine the empirical formula.
Determine the molar mass of the empirical compound.
ANSWERS
CHAPTER 6
INTERACTIVE LESSON
TEACHER’S
NOTES
Diabetes: Diagnosis and Management
Section 6.1
Diabetes is usually diagnosed by tests that reveal excess glucose
in a patient’s blood. Diabetes can be managed, often by diet
alone, reducing blood glucose back toward normal levels and
helping patients lead healthy lives. Match the correct type of
analysis to each blood glucose test apparatus.
quantitative
qualitative
Sodium Ions: Too much of a Good Thing?
Section 6.2
1. Complete the following statements using the words or phrases
below.
Sodium ions are needed to help regulate __________
fluid levels in the
body.
water
Excess sodium ions make the body retain __________,
which
blood pressure
raises _______________.
2. Match each quantity of sodium with Health Canada’s description.
1500 mg
●
●average Canadian intake
2300 mg
●
●recommended daily intake
3400 mg
●
●maximum tolerable limit
Section 6.3
What’s in a Mole?
Complete each statement by filling in the blank space(s).
•
•
•
carbon-12 has a mass of
A mole of __________
exactly 12 g.
In chemistry, an entity could be an
__________,
atom
__________,
ion
__________,
molecule
or __________.
formula unit
When measured, 1-mol samples of sucrose,
sodium chloride, and carbon have different
masses and volumes, but the same
__________
23
entities
number of __________,
6.02 × 10
.
Click the screen for a note:
Avogadro’s Constant is 6.02 × 1023.
sucrose
sodium
chloride
carbon
Calculating Amount from Mass
Section 6.4
A portion of French fries contains 1.15 g of sodium chloride, NaCl.
Calculate the amount of sodium chloride in 1.15 g. Use the given
data to complete the calculation.
g
g
Given: mNaCl = 1.15 g; Mna = 22.99
; MCl = 35.45
mol
mol
Required: amount of sodium chloride, nNaCl
Solution:
Step 1: Calculate to molar mass of sodium chloride, MNaCl.
MNaCl = 1(MNa) + 1(MCl)
g
g
35.45 mol
22.99 mol + __________
= __________
g
58.44
MNaCl = __________
mol
Step 2
Calculating Amount from Mass
Section 6.4
Step 2: Multiply the mass of sodium chloride by a conversion
factor of
1 mol
.
58.44 g
nNaCl =
1.15
nNaCl =
0.0196
g×
1 mol
58.44 g
mol
Statement: There are 0.0196 mol of sodium chloride in a 1.15 g
sample.
Calculating the Number of Ions in a Sample
Section 6.5
Determine the number of calcium and chloride ions in a 32.5 g
sample of calcium chloride. Use the given data to complete the
calculation.
Given: m
= 32.5 g ; MCa = 40.08
Ca2
Cl
g
g
; MCl = 35.45
mol
mol
Required: number of calcium and chloride ions, N Ca2+ and NClSolution:
Step 1: Calculate the molar mass of calcium chloride, M
.
Ca Cl
2
= 1(MCa) + 2(MCl)
M
Ca2
Cl
g
g
= 40.08 mol + 2( 35.45 mol
g
M
110.98
Ca2
Cl= __________
mol
)
Step 2
Calculating the Number of Ions in a Sample
Section 6.5
Step 2: Calculate the amount of calcium chloride using an
appropriate conversion factor.
1 mol
32.5
g
nC aC
= __________ g ×
2 l
110.98 g
0.29285 mol [carry five decimals]
nC aC
=
__________
l
2
Step 3
Calculating the Number of Ions in a Sample
Section 6.5
Step 3: Calculate the number of formula units in the 32.5 g sample.
formula units
23
0.29285
= (__________ mol ) ( 6.02 × 10
)
nC aC
2 l
1 mol
23
1.7630
×
10
nC aC
=
__________
formula units [carry four decimals]
2 l
Step 4
Calculating the Number of Ions in a Sample
Section 6.5
Step 4: Determine the number of each type of ion present.
1 calcium ion
NCa2+ = ( __________
)
1.7630 × 1023formula units) (
1 formula unit
1.76 × 1023 ions
NCa2+ = __________
2 chloride ions
NCl- = ( __________
1.7630 × 1023formula units) (
1 formula unit
3.53 × 1023 ions
NCl- = __________
)
Statement: A 32.5 g sample of calcium chloride contains
1.76 × 1023 calcium ions and __________
3.53 × 1023chloride ions.
__________
Determining an Empirical Formula
Section 6.7
Determine the empirical formula of a compound that contains 56.0%
vanadium and 44.0% oxygen. Use the data from the problem to
complete the calculation for Step 1.
Given: % V = 56.0 %; % O = 44.0 %; MV = 50.94 g/mol; MO = 16.00 g/mol
Required: empirical formula of the unknown compound, VxOy
56.0 g
Solution Step 1: A 100.0 g sample of this compound contains
44.0
of vanadium and __________
g of oxygen. Calculate the amount of each
element in the 100.0 g sample.
nV = (
56.0 g ) (
1 mol
)
50.94 g
1.0993 mol [carry four decimals]
nV = __________
nO = (
44.0
g)(
1 mol
16.00 g
)
2.7500 mol [carry four decimals]
nO = __________
Step 2
Determining an Empirical Formula
Section 6.7
Step 2: Divide the amount of each element by the smallest amount.
nv
nv
1.0993 mol
=
no
nv
Assign
1.0993 mol
2.7500 mol
=
=1
= __________
2.50
1.0993 mol
oxygen
a value of
2.50 , relative to vanadium
.
Step 3
Determining an Empirical Formula
Section 6.7
Step 3: These calculations give an empirical formula of V1O 2.5 .
Multiplying both subscripts by 2 gives V 2 O5 .
Statement: The empirical formula for the compound is
V2O5 .
Section 6.8
Chemical Fingerprinting
A mass spectrometer measures the masses of ionized entities by
measuring their deflection as they pass through a strong magnetic
field. Match the correct tag to each part of the diagram or to the graph.
ion
source
analyzer
detector
mass
spectrum
Answers for Discussion Questions:
Section 6.1
Slide 5
Sample answer: A quantitative instrument allows the diabetic person to
compare multiple readings taken at different times, such as before and after
meals. These numeric readings allow a diabetic patient to check on her
blood glucose level as it varies over time, so she can see how well she is
managing her diabetes (for instance, through diet). They let the patient
know the amount of glucose in her blood, rather than simply indicating that
there is or is not glucose in her blood.
Answers for Discussion Questions:
Section 6.2
Slide 7
Sample answer: Sodium is an important nutrient for human beings;
moreover it occurs naturally in many foods, so getting rid of it entirely would
mean processing these foods. However, if less salt were added to processed,
packaged foods, many people would find it easier to reduce the amount of
sodium they consume.
Answers for Discussion Questions:
Section 6.4
Slide 11
Sample answer: Calcium chloride has a slightly more complicated chemical
formula, CaCl2. So I would need to double the molar mass of chlorine (as well
as replacing the molar mass of sodium with that of calcium).
Answers for Discussion Questions:
Section 6.6
Slide 16
Answer: The mass of water, the number of water molecules, and the
numbers of atoms of each element are all greater on the left. The ratio of
hydrogen atoms to oxygen atoms is the same on both sides.
Answers for Discussion Questions:
Section 6.6
Slide 18
Sample answer: The law of definite proportions means that the ratio of each
pair of elements and ions in a chemical compound is always the same, so I
could use the ratio to determine a chemical formula that would always be
true.
Answers for Discussion Questions:
Section 6.8
Slide 23
Sample answer: Paper is one of the variables that scientists tried to control
in the British experiment. Canadian scientists would have to make sure that
their experiment used paper similar to that used in Canadian bills.
Credits
Slides 4 and 27: left Photos.com; right Cordelia Molloy/Photo Researchers,
Inc.
Slides 8 and 29: Dave Starrett