Toxins Unit
Investigation I:
Dissolving Toxins
Lesson 1: Lethal Dose
Lesson 2: Bearly Alive
Lesson 3: Mixing It Up!
Lesson 4: Weighing In
Lesson 5: Finding Solutions
Lesson 6: Holey Moley
Lesson 7: Is It Toxic?
Toxins Unit – Investigation I
Lesson 1:
Lethal Dose
ChemCatalyst
• Which substance do you think is most
toxic to you – alcohol (ethanol, C2H6O),
aspirin (salicylic acid, C7H6O3), or
arsenic (As)? Explain your thinking.
• How do you think toxicity is
determined?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• How is the toxicity of a substance
measured and described?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Calculate the toxicity of substances
based on the lethal dose.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
• Lethal dose (LD50) is the amount of an
ingested substance that kills 50
percent of a test sample. It is
expressed in mg/kg, or milligrams of
substance per kilogram of body weight.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: In this activity you will
compare the toxicity of various
substances.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• How is dosage related to toxicity?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
Methadone is a medication used as a
painkiller and as a treatment for those
recovering from heroin addiction. The LD50
for methadone is 95 mg/kg.
• Would you consider methadone to be
more or less toxic than acetaminophen
(LD50 = 2404 mg/kg) or aspirin (LD50 =
200 mg/kg)?
• Explain how you would calculate the
amount of this substance that would be
lethal to a 120-pound human.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• Toxicity is relative to dosage: The
toxicity (or therapeutic effect) of a
substance depends on the dose in
which it is received.
• The lethal dose (or therapeutic dose)
of a substance is often expressed as a
ratio between a certain mass of the
substance and one kilogram of the
body weight of an organism exposed
to the substance.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 2:
Bearly Alive
ChemCatalyst
• Drinking water in our homes contains
low concentrations of dissolved
chlorine, a highly toxic substance. Why
can we drink the water?
• What do you think concentration
means?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• What are the components of solutions,
and how are the concentrations of
solutions described?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Identify the components of solutions and
explain their relationship to the concept
of solution concentration.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
• A solution is a mixture of two or more
substances that is uniform throughout.
The substance in the greatest amount is
called the solvent. The solute is
dissolved in the solvent.
• Concentration is the amount of solute
for a specified amount of solvent. A
common measure of concentration is
moles per L, moles/L, which is referred to
as molarity, M.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: This activity introduces you to
solution chemistry and allows you to
examine solutions of differing
concentrations.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Solution
Water
Solute
Observations
Rank the bear size
from 1-8
—
0.1 M sugar
C12H22O11
1.0 M sugar
C12H22O11
2.0 M sugar
C12H22O11
Corn syrup
C12H22O11
0.1 M salt
NaCl
0.5 M salt
NaCl
1.0 M salt
NaCl
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
What do you think is happening in this
activity? Write a paragraph explaining your
ideas. Include your answers to the
following questions:
• What causes the size of the gummy
bears to change?
• Why are the gummy bears in the sugar
solutions ranked the way they are?
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• Why are the gummy bears in the salt
solutions different sizes than the
gummy bears in the sugar solutions of
the same concentration?
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• The movement of substances from an
area of high concentration to an area of
lower concentration is called diffusion.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• What would happen if you placed a
gummy bear in a 1.5 M sugar solution
overnight? Use your data table to help
you determine the outcome. Draw a
picture showing which molecules are
moving. Explain your answer in terms
of diffusion of water into or out of the
bear.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• A solution is a mixture that is uniform
throughout. The substance in the
greatest amount is the solvent. The
substance that is dissolved is the
solute.
• Molarity tells us how many particles or
molecules are in solution. Molarity is a
measure of the concentration of a
solution.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• Diffusion is defined as the movement of
molecules from an area of higher
concentration of that molecule to an area
of lower concentration of that molecule.
• Salts dissolve in water to give two (or
more) ions. Molecular substances do not
dissociate; they remain intact as individual
molecules.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 3:
Mixing It Up!
ChemCatalyst
• List three things that dissolve in water.
• List three things that do not dissolve in
water.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• What is solubility, and how is it
determined?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Explain the concept of solubility and
determine the solubility of a substance.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
• Homogeneous: A mixture in which the
substances are distributed uniformly.
All solutions are homogeneous by
definition.
• Heterogeneous: A mixture that is not
uniform throughout.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: In this activity you will
examine the solubility of five solutes in
water.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Test
tube
Solute
#1
ethanol
C2H6O (l)
#2
butanol
C4H10O (l)
#3
oil
C20H42 (l)
copper sulfate
CuSO4 (s)
carbon dioxide
CO2 (g)
#4
#5
after Step 1
after Step 2
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Dye molecules
View 1: Uniform
distribution of
molecules
View 2: More
molecules at
the bottom
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• Explain how you can tell when a
substance is soluble or insoluble in
water.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
• A solute is a gas, liquid, or solid that
dissolves when mixed with another
substance.
• A solvent is the substance present in
the greatest quantity in a solution.
Solvents are usually liquids.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• Soluble substances are solutes that
dissolve completely.
• Insoluble substances are those that
do not dissolve at all.
• Partially soluble substances are
those for which only a certain amount
will dissolve. Many substances are
partially soluble.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• There is solid sugar at the bottom of
your tea. Why do the last sips taste
sweeter?
• All of the sugar in your tea is dissolved.
The last sips taste the same as the
first. Use a molecular view of sugar
dissolved in water to explain why.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• Gases, liquids, and solids can dissolve
in water. However, some substances
are not soluble.
• Partially soluble means that when two
substances are mixed, a solution forms
but one substance is leftover.
• Solutions are homogeneous. The
molecules or ions of the solute are
distributed uniformly between the
solvent molecules.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 4:
Weighing In
ChemCatalyst
• Which do you think is more toxic—one
mole of arsenic, As, or ten grams of
arsenic? Explain your reasoning.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• How is the mole concept used to
connect the mass of a sample to the
number of particles it contains?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Use the molar mass of a substance to
find the number of molecules in a
sample.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: The purpose of today's lesson
is to explore the relationship between
mass and moles.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Rice
Lentils
Volume of each
Mass of the baggie
Mass of ten pieces
Mass of one piece
(calculated)
# of pieces
(calculated)
# of pieces
(counted)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
substance
# of particles
# of moles
He (g)
6.02  1023
1 mole
He (g)
1.204  1024
2 moles
8.0 g
1 mole
27.0 g
Al (s)
Cu (s)
6.02  1023
1 mole
As (s)
6.02  1023
1 mole
NaCl (s)
6.02  1023
1 mole
MgF2 (s)
measured mass
31.2 g
MgF2 (s)
6.02  1023
H2O (l)
3.01  1023
H2O (l)
6.02  1023
1 mole
C6H12O6
6.02  1023
1 mole
1 mole
62.3 g
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• How is measuring the mass of a
substance the same as counting?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
• The molar mass of a substance is
how much one mole of that substance
weighs. Molar mass is the sum of all of
the atomic masses (in grams) in a
chemical formula.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
molar mass in
grams/mole
mass in grams
weight of the substance
add the atomic weights of
the atoms in the chemical
formula
moles
6.02  1023 (Avogadro’s
number) of each of the
atoms in the chemical
formula
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• You have one mole of NaCl and one
mole of KCl. Which one weighs more?
Explain your thinking.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• The atomic weight on the periodic
table is equivalent to the mass of 1
mole of atoms of the element in grams.
• The molar mass of a compound is the
sum of the atomic weights of the atoms
in the compound.
• Molar mass allows you to convert
between moles and grams.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 5:
Finding Solutions
ChemCatalyst
Consider the following solutions:
1.0 L
1.0 M C6H12O6
(glucose)
1.0 L
1.0 M C12H22O11
(sucrose)
500 mL
1.0 M C12H22O11
(sucrose)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• Which solution has the most
molecules? Explain.
• Which solution has the greatest
concentration? Explain.
• Which solution weighs the most?
Explain.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• What are the methods that can be
used to produce a solution of a specific
concentration?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Produce a solution of specific
concentration by using the mass of
solute and its molar mass or by using
dilution.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: You will prepare four solutions
by two different methods.
Volume conversion: 1 L = 1000 mL
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
mass
moles
volume
molarity
342 g
34.2 g
1.0 mole
1.0 L
1.0 L
1.0 M
0.10 M
3.42 g
0.342 g
0.010 moles
100 mL
0.010 M
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
volume
100 mL
100 mL
10 mL
10 mL
molarity
moles
dilute
to
1.0 M
0.10 moles
1.0 L
0.10 M 0.010 moles
1.0 L
0.10 M 0.0010 moles 100 mL
0.010 M
100 mL
new
molarity
0.10 M
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Solution A
Method of
preparation
Concentration
Color
weighed 3.42 g
sugar, diluted to
100 mL
0.10 M
dark red
Solution B
Solution C
Solution D
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• Describe two ways to make a 0.010 M
sugar solution.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• How many moles of sucrose does 100
mL of a 0.10 M sucrose solution
contain?
• How many moles of sucrose does 25
mL of a 0.10 M sucrose solution
contain?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• When concentration is expressed in
moles of solute per liter of solution it is
referred to as molarity.
• Solutions of specific concentrations
can be created by weighing out the
solute or by dilution of an existing
solution of known concentration.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 6:
Holey Moley
ChemCatalyst
How would you calculate the total amount
of glucose, in grams, in the blood of an
average human?
Useful information:
• Blood volume = 5.5 L
• Glucose concentration = 0.0056 M
• Molar mass of glucose (C6H12O6) = 180
g/mol
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• What is the connection between the
mass of a solute, its molar mass, and
the concentration of solution it is in?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Convert between the mass of solute in
solution, its concentration, and its molar
mass.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes
Proportional analysis
Step 1: Convert liters to moles using the
concentration.
0.0056 moles glucose x moles glucose

1 L blood
5.5 L blood
x = 0.031 moles glucose
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes (cont.)
Step 2: Convert moles to grams using
the molar mass
180 g glucose
y g glucose

1 mole glucose 0.031 moles glucose
y = 5.5 g glucose
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Notes (cont.)
Dimensional analysis
0.0056 moles 180 g glucose
5.5 L blood 

 5.5 g glucose
1 L blood 1 mole glucose
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: You will practice solving
problems in which you convert between
mass of solute, moles of solute, and
liters of solution using molecular weight
and molarity.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
mass
moles
volume
342 g
1.0 mole
1.0 L
34.2 g
1.0 L
3.42 g
100 mL
0.342 g
27.4 g
molarity
0.10 M
0.10 M
0.080 moles
1.0 L
0.080 M
17.1 g
1.0 L
0.050 M
6.84 g
1.0 L
27.4 g
0.080 moles
17.1 g
0.050 moles
500 mL
0.040 M
0.025 M
500 mL
0.010 M
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
0.1 M sucrose 0.05 M sucrose 0.01 M sucrose
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
volume
molarity
moles
dilute to
new
molarity
1.0 L
1.0 M
1.0 moles
10.0 L
0.10 M
1.0 L
500 mL
250 mL
500 mL
0.10 M
1.0 M
1.0 M
0.10 M
10.0 L
1.0 L
1.0 L
1.0 L
250 mL
500 mL
250 mL
0.10 M
0.20 M
0.20 M
1.0 L
5.0 L
5.0 L
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• Explain how to make a glucose
solution that has the same
concentration as blood.
• Explain how to dilute a 1.0 M glucose
solution so that it has the same
concentration as human blood.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Sample Problems Involving Molarity
Sample Problem #1 – Calculating
molarity of a solution:
• What is the molarity of 5.5 L of blood
containing 10 grams of glucose?
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Sample Problem #2 – Calculating
grams of solute needed for a specific
molarity.
• How many grams of glucose, C6H12O6,
would you need to create 250 mL of
solution with a molarity of 0.0050
moles / liter?
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
• When a solution is diluted, solvent is
added without the addition of more solute.
Since the amount of solute is not
changed, our calculations reflect this fact.
# of moles before dilution =
# of moles after dilution
• Since the moles of solute is equal to the
molarity multiplied by the volume, we can
substitute these values into the equation.
M1V1 = M2V2
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Preparation of Solutions by Dilution
Sample Problem #1 – Calculate the
volume of a known solution needed to
dilute to a new molarity.
• What volume of 0.75 M glucose is
needed to make 1 liter of 0.15 M
glucose?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• How many grams of glucose would
you need to make 100 mL of 1.0 M
solution? The molecular formula of
glucose is C6H12O6.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• Mass of solute, moles of solute, and
volume of solution are related to one
another by the molecular weight of the
solute and the concentration of the
solution.
• If you have a certain volume of a
solution of a specified concentration,
then you know how many moles of
solute you have.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Toxins Unit – Investigation I
Lesson 7:
Is It Toxic?
ChemCatalyst
Suppose you wanted to determine if your
tap water contained lead sulfate, PbSO4
(which is toxic).
• Do you expect the weight of 100 ml of
pure water to be the same as that of a
100 ml solution containing PbSO4?
Explain your reasoning.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
The Big Question
• What does the mass of a solution
reveal about the concentration and the
molar mass of its solute?
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
You will be able to:
Deduce some differences among
solutions that look identical.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Activity
Purpose: You will determine the
identities of solutions given to you by
your instructor, and decide which is safe
to drink.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Safety note: Do not get NaOH on your
skin. In case of a spill, rinse with large
amounts of water. Wear goggles.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Making Sense
• Examine the toxicities given below.
Which solution would be most harmful
if you drank it? Which would be least
harmful to drink? Explain your thinking.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
(cont.)
Salt
Molar
mass
Mass of 1.0
moles salts
KCl
74.55 g
74.55 g
NaBr
102.89 g
102.9 g
NaOH
40.00 g
40.00 g
Approximate
mass of 50 mL
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Check-In
• Place the following 1.0 M solutions in
order of increasing mass, from the
smallest mass to the largest mass:
NaCl, KCl, and CaCl2.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X
Wrap-Up
• Solutions have different masses
depending on the molar mass of the
solute.
• Pure water weighs exactly 1.0 g per
1.0 mL. If 1.0 mL weighs more or less
than this, then the water is not pure.
© 2004 Key Curriculum Press.
Unit IV • Investigation I-X