Toxins Unit
Investigation II:
Tracking Toxins
Lesson 1: The Language of Change
Lesson 2: Making Predictions
Lesson 3: Spare Change?
Lesson 4: Scrub the Air
Lesson 5: Some Things Never Change
Lesson 6: Atom Inventory
Lesson 7: Toxins At Work
Toxins Unit – Investigation II
Lesson 1:
The Language of Change
ChemCatalyst
Below is a chemical “sentence” describing
the formation of a very toxic substance,
hydrogen cyanide.
NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g)
• What kinds of information does this
chemical notation contain? List at least
four pieces of information contained in this
chemical notation.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• How do chemists describe chemical
reactions, and what kinds of evidence
do they look for to verify that their
descriptions are correct?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Identify the different components of a
chemical equation and use that
information to predict the outcome of the
reaction it represents.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• The previous chemical “sentence” is
called a chemical equation. A chemical
equation describes change.
(cont.)
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Unit IV • Investigation II-X
Notes (cont.)
•The substances you start with before the
change takes place are on the left side of
the arrow. If there is more than one
substance and they react with one
another, they are called reactants.
•The substances you end up with after
the change takes place are on the right
side of the arrow. They are often referred
to as products.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: In this experiment, you will
carry out the reaction between
hydrochloric acid and sodium
bicarbonate, and then do some analysis
of the products that form.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Safety note: Hydrochloric acid is
dangerous and causes burns. Do not
get hydrochloric acid on your skin. In
case of a spill, rinse with large
amounts of water. Wear goggles.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Symbol
What it
Represents
Symbol
HCl
NaCl
(aq)
H2O
+
(l)
NaHCO3
CO2

(g)
What it
Represents
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Observations
During Reaction
Observations
After Reaction
Observations
During Heating
Observations
After Heating
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Unit IV • Investigation II-X
Making Sense
• Describe how a chemical equation
keeps track of a chemical reaction.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
HCl(aq) + NaHCO3(aq) 
NaCl(aq) + H2O(l) + CO2(g)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
Consider the following reaction between
sodium cyanide and a solution of
hydrochloric acid.
NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g)
• Describe in detail what you would observe
if you carried out this reaction.
• Describe the products that you would
have.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• Chemical equations help chemists
keep track of the substances involved
in chemical and physical changes.
• Chemical equations indicate the
reactants and products of chemical
reactions.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 2:
Making Predictions
ChemCatalyst
Consider the following reaction:
AgNO3 (aq) + KCl (aq) 
KNO3(aq) + AgCl(s)
• What do you expect to observe if you
carried out the reaction?
• Translate the above chemical equation
into writing, describing what is taking
place.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• How do chemists predict the products
of reactions and write the chemical
reactions they represent?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Use chemical reactions to predict
expected real-world observations and
use real-world observations to write the
chemical reaction they represent.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: This lesson provides you with
practice translating chemical equations.
You will have the opportunity to check
you predictions by completing the
laboratory procedure associated with
each equation.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Safety note: Do not touch the dry ice
with your fingers. It causes burns.
NaOH, Ca(OH)2, and NH4OH are
caustic. Do not get them on your skin.
In case of a spill, rinse with large
amounts of water. Wear goggles.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Reaction
Predictions Observations
Dry ice
1 CO2 (s)  CO2 (g)
2 a) CO2 (s)  CO2 (g)
b) CO2 (s) + H2O (l) 
H2CO3 (aq)
3 CO2 (s) + Ca(OH)2 (aq) 
CaCO3 (s) + H2O (aq)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Reaction
Predictions Observations
Calcium chloride
4 a) CaCl2 (s)  CaCl2 (aq)
b) CaCl2(s) 
Ca2+(aq) + 2 Cl– (aq)
5 CaCl2 (aq) + 2 NaOH (aq) 
Ca(OH)2 (s) + 2 NaCl (aq)
6 CaCl2 (s) + CuSO4 (s) 
CaCl2 (s) + CuSO4 (s)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Reaction
Predictions Observations
Copper sulfate
7 a) CuSO4 (s)  CuSO4 (aq)
b) CuSO4 (s) 
Cu2+ (aq) + SO42–(aq)
8 CuSO4 (s) + 4 NH4OH (aq) 
Cu(NH3)4SO4 (aq) + 4H2O (l)
9 CuSO4 (aq) + Zn (s) 
Cu (s) + ZnSO4 (aq)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
• Make a list of all the different types of
things that you observed today that are
associated with changes in matter.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
• No Check-In exercise.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• Chemical equations allow chemists to
predict and track changes in matter.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 3:
Spare Change?
ChemCatalyst
The following two equations both describe
what happens when dry ice is placed in
water:
CO2 (s)  CO2 (g)
CO2 (s) + H2O (l)  H2CO3 (aq)
• What differences do you see in these
two equations?
• Why do you think two equations are
needed to describe what happens?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• What are the differences between
physical changes and chemical
changes?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Convert back and forth between
chemical reaction notation and real world
observations, and identify each change
as either chemical or physical.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• In a chemical equation describing a
physical change, the chemical
formulas do not change in going from
reactants to products. However, the
phase (s, l, & aq) does change.
• In a chemical equation describing a
chemical change, the chemical
formulas of the reactants are different
from those of the products.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: This activity provides you with
practice distinguishing between physical
and chemical changes using only the
chemical equations.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
• Compare your observations for each
reaction to the chemical equations. If
you were asked to classify a reaction
as a physical or chemical change,
which would you prefer to have, a set
of observations or chemical equations?
Explain your thinking.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
CaCl2 (s)  CaCl2 (aq)
CaCl2(s)  Ca2+(aq) + 2 Cl– (aq)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
• Does the following chemical equation
describe a physical change or a
chemical change? Explain how you
can tell.
C17H17O3N(s) + 2C4H6O3(l) 
C21H21O5N(s) + 2 C2H4O2(l)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• Chemical changes involve the
formation of new substances. Physical
changes, such as phase changes,
involve a change in form.
• Chemical equations often provide
more straightforward information about
the type of change than mere
observations.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 4:
Scrub the Air
ChemCatalyst
In enclosed spaces such as on a space
station or in a submarine, the breathing
of the occupants causes a natural build
up of carbon dioxide, CO2. Too much
CO2 in the air is highly toxic.
• List two ways to use chemical change
to eliminate CO2 (g).
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• How does molecular bonding affect the
outcome of chemical reactions?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Classify certain chemical reactions as
either combination or decomposition and
predict the possible products when given
specific reactants.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• In a decomposition reaction, one
reactant is broken apart into two or
more substances. In a combination
reaction, two or more substances
combine to form a single product.
AB  A + B (decomposition)
A + B  AB (combination)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
CaCO3 
CaO
+
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: You will compare different
kinds of chemical reactions and learn the
notation used to write chemical
reactions.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
• Explain how you can predict the
products of the decomposition of NaCl.
• Explain how you can predict the
product of the combination of carbon
and hydrogen.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
• List a possible product of the following
combination reaction:
CH4 (g) + O2 (g) 
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• The substances in chemical reactions
obey the bonding rules we have
learned for ionic and covalent
substances.
• A decomposition reaction in one in
which one reactant is broken apart into
two or more substances.
• A combination reaction is one in which
two or more substances combine to
form a single product.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 5:
Some Things Never
Change
ChemCatalyst
Consider the following reaction.
Na2CO3 (aq) + CaCl2 (aq) 
NaCl (aq) + CaCO3 (s)
• Describe what you will observe when
Na2CO3 (aq) and CaCl2 (aq) are
mixed.
• Will the mass increase, decrease, or
stay the same after mixing? Explain.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• What is the relationship between the
mass of reactants and the mass of
products of a chemical reaction?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Explain the relationship between the
mass of reactants and the mass of
products of a chemical reaction.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: In this activity, you will explore
conservation of matter and how it applies
to the world around you.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Weight
before
mixing
Predict the
weight after
mixing
Observations
after mixing
Weight
after
mixing
Na2CO3 (aq) +
CaCl2 (aq)
Na2CO3 (aq) +
C2H4O2 (aq)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Chemical Reaction 1:
>
=
?
?
<
Reactants
Products
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Chemical Reaction 2:
>
?
Reactants
=
<
?
Products
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
• In your own words, explain what
happens to matter and its mass when
a chemical reaction or physical change
occurs.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• Law of conservation of matter:
Matter can be neither created nor
destroyed in chemical reactions. This
means that in chemical reactions and
physical changes atoms do not come
in and out of existence. They are
simply rearranged. Since atoms have
mass, the mass does not change.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
Consider the following reaction:
CuCO3 (s) + H2SO4 (aq) 
CO2 (g) + CuSO4 (aq) + H2O (l)
• Describe what you will observe when
CuCO3 (s) and H2SO4 (aq) are mixed.
• Will the mass increase, decrease, or
stay the same after mixing? Explain.
• Will the weight increase, decrease, or
stay the same after mixing? Explain.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• Individual atoms are conserved in
chemical reactions and physical
changes: the number of atoms of each
element remains constant from start to
finish.
• Matter is conserved in chemical
reactions: the total mass of the
products equals the total mass of the
reactants.
• Gases have mass.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 6:
Atom Inventory
ChemCatalyst
• Does the following equation obey the
law of conservation of matter? Why or
why not?
CuCl2(aq) + Na2S (aq) 
CuS (s) + NaCl (aq)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• What does it mean to “balance” a
chemical equation?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Use the concept of a balanced chemical
equation to account for the atoms
involved in a chemical reaction.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• The subscripts in a chemical equation
indicate how many atoms are in the
chemical formula for that substance.
• The large numbers in front of chemical
formulas are called coefficients. They
indicate how many parts of that
substance there are in a reaction.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: In this activity, you will practice
balancing chemical reactions.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
The four unbalanced reactions are given
below:
1. Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)
2. O2(g) + H2(g)  H2O(l)
3. O2(g) + CH4(g)  CO2 + H2O(l)
4. NO2 + H2O(l)  HNO3(aq) + NO(g)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
The balanced equations are shown below,
with the new coefficients highlighted in bold.
1. Zn (s) + 2 HCl (aq)  ZnCl2 (aq) + H2
(g)
2. O2 (g) + 2 H2 (g)  H2O (l)
3. 2 O2 (g) + CH4 (g)  CO2 (g) + 2 H2O (l)
4. 3 NO2 (g) + H2O (l) 
2 HNO3 (aq) + NO (g)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
C2H6 + 4 O2  2 CO2 + 3 H2O
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Example #1: Balance the following
equation
NO (g) + O2 (g)  NO2 (g)
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Example #2: Balance the following
equation for rusting iron.
Fe (s) + O2 (g)  Fe2O3 (s)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
• Balance the following equation.
Ca + O2  CaO
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• In order to conserve matter, the
number of atoms on both sides of a
chemical equation must be equal.
• When an equation is balanced it tells
you how many molecules or moles of
each substance take part in a reaction
and how many molecules or moles of
product (s) are produced.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Toxins Unit – Investigation II
Lesson 7:
Toxins At Work
ChemCatalyst
Hemoglobin (Hb) is the molecule in your
blood that carries oxygen throughout
your body. Ca3(PO4)2 (s), calcium
phosphate, is the main compound in
bones and teeth.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
(cont.)
Below are two reactions that might take place
in your body, one involving carbon monoxide,
CO, and the other involving lead chloride,
PbCl2.
O2–Hb (aq) + CO (g)  CO–Hb (aq) + O2 (g)
Ca3(PO4)2 (s) + Pb(NO3)2 (aq) 
Pb3(PO4)2(OH) (s) + Ca(NO3)2 (aq)
• Which atoms rearranged in each case?
• Why are CO and PbCl2 toxic?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
The Big Question
• How do toxins act upon our bodies?
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
You will be able to:
Recognize single displacement and
double displacement reactions and
predict the possible products when given
specific reactants.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
Single displacement: A single
displacement reaction begins with an
element and a compound. The
compound breaks apart and then one
piece combines with the element while
the other piece is left in the elemental
form. The general reaction can be written
as AB + C  AC + B, where C displaces
B.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes (cont.)
Double displacement: A double
displacement reaction begins with two
compounds that break apart. Their parts
then recombine into two new products.
The general reaction can be written as
AB + CD  AD + CB, where B and D
exchange with one another (or A and C
exchange with one another).
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes (cont.)
• Groups of atoms are called
polyatomic ions.
• The atom or groups of atoms that
move around in chemical reactions are
called species.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes (cont.)
Single displacement reactions:
Cl2 + CaI2  [CaCl2 + I2]
Note that the products [Ca + 2ClI] are
not produced.
Mg + 2HCl  [H2 + MgCl2]
Note that the products [Cl2 + MgH2] are
not produced.
(cont.)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes (cont.)
Double displacement reactions:
CsF + NaOH  [CsOH + NaF]
Note that the products [CsNa + FOH] are
not produced.
PbI2 + 2K2S  [PbS + 2KI]
Note that the products [K2Pb + SI2] are
not produced.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Activity
Purpose: In this worksheet, you will
practice predicting the products of
displacement reactions.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Making Sense
• Explain in a step-by-step fashion how
you completed the above equations.
• Suppose you drank a solution
containing the toxin PbI2. Suggest how
this toxin may act in your body.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Notes
• Combination:A + B  AB
• Decomposition: AB  A + B
• Single displacement: AB + C  AC + B
• Double displacement: AB + CD  AD +
BC
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Check-In
Thallium is the 81st element on the periodic
table. Not that long ago, thallium
compounds were used both as rat poison
and in hair removal products. However,
these compounds are quite toxic to humans
and hair loss is one of the first signs of
thallium poisoning.
Predict the products of the following
reaction and balance the equation.
TlCl3 + LiOH 
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X
Wrap-Up
• Many chemical reactions can be
classified as displacement reactions, in
which one part of a compound is
exchanged by another.
• Toxins act by displacing pieces of
compounds in your body.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X