Toxins Unit

1
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
2
Toxins Unit Investigation II

• Lesson 1
• The Language of Change

3
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.

4
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?

5
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.

6

Notes

• The previous chemical sentence is called a
  chemical equation. A chemical equation describes
  change.

(cont.)
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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.

8
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.)
9
(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.)
10
(cont.)
Symbol What it Represents Symbol What it Represents
HCl NaCl
(aq) H2O
(l)
NaHCO3 CO2
? (g)
(cont.)
11
(cont.)
Observations During Reaction
Observations After Reaction
Observations During Heating
Observations After Heating
12
Making Sense

• Describe how a chemical equation keeps track of a
  chemical reaction.

13
Notes

• HCl(aq) NaHCO3(aq) ?
• NaCl(aq) H2O(l) CO2(g)

14
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.

15
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.

16
Toxins Unit Investigation II

• Lesson 2
• Making Predictions

17
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.

18
The Big Question

• How do chemists predict the products of reactions
  and write the chemical reactions they represent?

19
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.

20
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.)
21
(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.)
22
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)
23
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)
24
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)
25
Making Sense

• Make a list of all the different types of things
  that you observed today that are associated with
  changes in matter.

26
Check-In

• No Check-In exercise.

27
Wrap-Up

• Chemical equations allow chemists to predict and
  track changes in matter.

28
Toxins Unit Investigation II

• Lesson 3
• Spare Change?

29
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?

30
The Big Question

• What are the differences between physical changes
  and chemical changes?

31
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.

32
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.

33
Activity

• Purpose This activity provides you with practice
  distinguishing between physical and chemical
  changes using only the chemical equations.

34
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.

35

Notes

• CaCl2 (s) ? CaCl2 (aq)
• CaCl2(s) ? Ca2(aq) 2 Cl (aq)

36
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)

37
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.

38
Toxins Unit Investigation II

• Lesson 4
• Scrub the Air

39
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).

40
The Big Question

• How does molecular bonding affect the outcome of
  chemical reactions?

41
You will be able to

• Classify certain chemical reactions as either
  combination or decomposition and predict the
  possible products when given specific reactants.

42
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.)
43
(cont.)

• CaCO3 ? CaO

44
Activity

• Purpose You will compare different kinds of
  chemical reactions and learn the notation used to
  write chemical reactions.

45
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.

46
Check-In

• List a possible product of the following
  combination reaction
• CH4 (g) O2 (g) ?

47
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.

48
Toxins Unit Investigation II

• Lesson 5
• Some Things Never Change

49
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.

50
The Big Question

• What is the relationship between the mass of
  reactants and the mass of products of a chemical
  reaction?

51
You will be able to

• Explain the relationship between the mass of
  reactants and the mass of products of a chemical
  reaction.

52
Activity

• Purpose In this activity, you will explore
  conservation of matter and how it applies to the
  world around you.

(cont.)
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(cont.)
Weight before mixing Predict the weight after mixing Observations after mixing Weight after mixing
Na2CO3 (aq) CaCl2 (aq)
Na2CO3 (aq) C2H4O2 (aq)
(cont.)
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Chemical Reaction 1
(cont.)
(cont.)
55
Chemical Reaction 2
(cont.)
56
Making Sense

• In your own words, explain what happens to matter
  and its mass when a chemical reaction or physical
  change occurs.

57

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.

58
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.

59
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.

60
Toxins Unit Investigation II

• Lesson 6
• Atom Inventory

61
ChemCatalyst

• Does the following equation obey the law of
  conservation of matter? Why or why not?
• CuCl2(aq) Na2S (aq) ?
• CuS (s) NaCl (aq)

62
The Big Question

• What does it mean to balance a chemical
  equation?

63
You will be able to

• Use the concept of a balanced chemical equation
  to account for the atoms involved in a chemical
  reaction.

64
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.

65
Activity

• Purpose In this activity, you will practice
  balancing chemical reactions.

(cont.)
66
(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)

67
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.)
68

(cont.)

• C2H6 4 O2 ? 2 CO2 3 H2O

(cont.)
69
(cont.)

• Example 1 Balance the following equation
• NO (g) O2 (g) ? NO2 (g)

(cont.)
70
(cont.)

• Example 2 Balance the following equation for
  rusting iron.
• Fe (s) O2 (g) ? Fe2O3 (s)

71
Check-In

• Balance the following equation.
• Ca O2 ? CaO

72
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.

73
Toxins Unit Investigation II

• Lesson 7
• Toxins At Work

74
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.)
75
(cont.)

• Below are two reactions that might take place in
  your body, one involving carbon monoxide, CO, and
  the other involving lead chloride, PbCl2.
• O2Hb (aq) CO (g) ? COHb (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?

76
The Big Question

• How do toxins act upon our bodies?

77
You will be able to

• Recognize single displacement and double
  displacement reactions and predict the possible
  products when given specific reactants.

78
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.)
79
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.)
80
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.)
81
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.)
82
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.

83
Activity

• Purpose In this worksheet, you will practice
  predicting the products of displacement
  reactions.

84
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.

85
Notes

• Combination A B ? AB
• Decomposition AB ? A B
• Single displacement AB C ? AC B
• Double displacement AB CD ? AD BC

86
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 ?

87
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.