Toxins Unit

1
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?
2
Toxins Unit Investigation I

• Lesson 1
• Lethal Dose

3
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?

4
The Big Question

• How is the toxicity of a substance measured and
  described?

5
You will be able to

• Calculate the toxicity of substances based on the
  lethal dose.

6
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.

7
Activity

• Purpose In this activity you will compare the
  toxicity of various substances.

8
Making Sense

• How is dosage related to toxicity?

9
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.

10
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.

11
Toxins Unit Investigation I

• Lesson 2
• Bearly Alive

12
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?

13
The Big Question

• What are the components of solutions, and how are
  the concentrations of solutions described?

14
You will be able to

• Identify the components of solutions and explain
  their relationship to the concept of solution
  concentration.

15
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.

16
Activity

• Purpose This activity introduces you to solution
  chemistry and allows you to examine solutions of
  differing concentrations.

(cont.)
17
Solution Solute Observations Rank the bear size from 1-8
Water
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
18
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.)
19
(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.)
20

(cont.)

• The movement of substances from an area of high
  concentration to an area of lower concentration
  is called diffusion.

21
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.

22
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.)
23
(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.

24
Toxins Unit Investigation I

• Lesson 3
• Mixing It Up!

25
ChemCatalyst

• List three things that dissolve in water.
• List three things that do not dissolve in water.

26
The Big Question

• What is solubility, and how is it determined?

27
You will be able to

• Explain the concept of solubility and determine
  the solubility of a substance.

28
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.

29
Activity

• Purpose In this activity you will examine the
  solubility of five solutes in water.

(cont.)
30
Test tube Solute after Step 1 after Step 2
1 ethanol C2H6O (l)
2 butanol C4H10O (l)
3 oil C20H42 (l)
4 copper sulfate CuSO4 (s)
5 carbon dioxide CO2 (g)
31
(cont.)
32
Making Sense

• Explain how you can tell when a substance is
  soluble or insoluble in water.

33
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.)
34
(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.

35
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.

36
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.

37
Toxins Unit Investigation I

• Lesson 4
• Weighing In

38
ChemCatalyst

• Which do you think is more toxicone mole of
  arsenic, As, or ten grams of arsenic? Explain
  your reasoning.

39
The Big Question

• How is the mole concept used to connect the mass
  of a sample to the number of particles it
  contains?

40
You will be able to

• Use the molar mass of a substance to find the
  number of molecules in a sample.

41
Activity

• Purpose The purpose of today's lesson is to
  explore the relationship between mass and moles.

(cont.)
42
(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.)
43
(cont.)
substance of particles of moles measured mass
He (g) 6.02 ? 1023 1 mole
He (g) 1.204 ? 1024 2 moles 8.0 g
Al (s) 1 mole 27.0 g
Cu (s) 6.02 ? 1023 1 mole
As (s) 6.02 ? 1023 1 mole
NaCl (s) 6.02 ? 1023 1 mole
MgF2 (s) 31.2 g
MgF2 (s) 6.02 ? 1023 1 mole 62.3 g
H2O (l) 3.01 ? 1023
H2O (l) 6.02 ? 1023 1 mole
C6H12O6 6.02 ? 1023 1 mole
44
Making Sense

• How is measuring the mass of a substance the same
  as counting?

45
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.)
46
(cont.)
47
Check-In

• You have one mole of NaCl and one mole of KCl.
  Which one weighs more? Explain your thinking.

48
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.

49
Toxins Unit Investigation I

• Lesson 5
• Finding Solutions

50
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.)
51
(cont.)

• Which solution has the most molecules? Explain.
• Which solution has the greatest concentration?
  Explain.
• Which solution weighs the most? Explain.

52
The Big Question

• What are the methods that can be used to produce
  a solution of a specific concentration?

53
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.

54
Activity

• Purpose You will prepare four solutions by two
  different methods.
• Volume conversion 1 L 1000 mL

(cont.)
55
(cont.)
mass moles volume molarity
342 g 1.0 mole 1.0 L 1.0 M
34.2 g 1.0 L 0.10 M
3.42 g 0.010 moles 100 mL
0.342 g 0.010 M
(cont.)
56
(cont.)
volume molarity moles dilute to new molarity
100 mL 1.0 M 0.10 moles 1.0 L 0.10 M
100 mL 0.10 M 0.010 moles 1.0 L
10 mL 0.10 M 0.0010 moles 100 mL
10 mL 0.010 M 100 mL
(cont.)
57
(cont.)
Method of preparation Concentration Color
Solution A weighed 3.42 g sugar, diluted to 100 mL 0.10 M dark red
Solution B
Solution C
Solution D
58
Making Sense

• Describe two ways to make a 0.010 M sugar
  solution.

59
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?

60
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.

61
Toxins Unit Investigation I

• Lesson 6
• Holey Moley

62
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

63
The Big Question

• What is the connection between the mass of a
  solute, its molar mass, and the concentration of
  solution it is in?

64
You will be able to

• Convert between the mass of solute in solution,
  its concentration, and its molar mass.

65
Notes

• Proportional analysis
• Step 1 Convert liters to moles using the
  concentration.
• x 0.031 moles glucose

(cont.)
66
Notes (cont.)

• Step 2 Convert moles to grams using the molar
  mass
• y 5.5 g glucose

(cont.)
67
Notes (cont.)

• Dimensional analysis

68
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.)
69
mass moles volume molarity
342 g 1.0 mole 1.0 L
34.2 g 1.0 L 0.10 M
3.42 g 100 mL
0.342 g 0.10 M
27.4 g 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 500 mL 0.040 M
17.1 g 0.050 moles 0.025 M
500 mL 0.010 M
70
(cont.)
0.1 M sucrose
0.01 M sucrose
0.05 M sucrose
(cont.)
71
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 0.10 M 10.0 L
500 mL 1.0 M 1.0 L
250 mL 1.0 M 1.0 L
500 mL 0.10 M 1.0 L
250 mL 0.10 M 1.0 L
500 mL 0.20 M 5.0 L
250 mL 0.20 M 5.0 L
72
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.)
73
(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.)
74
(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.)
75
(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.)
76
(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?

77
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.

78
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.

79
Toxins Unit Investigation I

• Lesson 7
• Is It Toxic?

80
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.

81
The Big Question

• What does the mass of a solution reveal about the
  concentration and the molar mass of its solute?

82
You will be able to

• Deduce some differences among solutions that look
  identical.

83
Activity

• Purpose You will determine the identities of
  solutions given to you by your instructor, and
  decide which is safe to drink.

(cont.)
84
(cont.)

• Safety note Do not get NaOH on your skin. In
  case of a spill, rinse with large amounts of
  water. Wear goggles.

(cont.)
85
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.)
86
(cont.)
Salt Molar mass Mass of 1.0 moles salts Approximate mass of 50 mL
KCl 74.55 g 74.55 g
NaBr 102.89 g 102.9 g
NaOH 40.00 g 40.00 g
87
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.

88
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.