Green Chemistry
Name: Judy Sidileau
Mascenic Regional High School
Contact info: jsidileau@mascenic.org
Topic: Precipitates Lab

Learning Objectives:
(i) Understand solubility rules and be able to apply them to predict the products of reactions.
(ii) Balance chemical equations and use these equations to perform stoichiometric calculations
of product yield.
(iii) Use stoichiometry to predict limiting reagent vs. reagent in excess.
(iv) Use critical thinking skills to determine mini-experiments in order to prove identity of
precipitate.
(v) Predict the identities of dissolved ions based upon visually inspecting color of filtrate.
(vi) Use Excel graphing program to determine limiting reagent based upon using class data in
which one reactant volume is held constant and varying volume used of other reactant.
Green Chemistry Principles:
(i) Would like to omit use of sodium phosphate (phosphates in the environment) as well as the production of cobalt phosphate, which is hazardous. The problem is cobalt (II) nitrate is a lovely red color; sodium phosphate is colorless. The cobalt (II) phosphate formed is a lovely purple-blue ppt. The students can easily identify their ppt in parts I and II of the lab via color as well as identify limiting reagent visually to helps kids confirm what they theoretically know.
(ii) Would like to scale down amounts used so waste generated is less. Typically my classes work in pairs.
(iii) Other green ideas???

Procedure: (From Inquiries Into Chemistry, by Abraham and Pavelich, c. 1991.
Part I. Dissolve a small amount ((~ 1 cc) of solid cobalt (II) nitrate in about 20 mL of distilled water. Dissolve a similar amt of sodium phosphate in a 2nd 20 mL portion of water Describe the appearance of each solution. Pour half of each solution into a third beaker and mix thoroughly. (Save the mixture and 2 solutions for later use). Describe the appearance of of the misture. Assuming the reaction involves the dissolved ions, hypothesize the possible identitites of the solid formed in the mixture. Carry out experiments which would distinguish between all the possibilities. Describe the results of these experiments.Separate the mixture by filtration. Note the characteristics of the supernatant, and predict which ions might be dissolved in it. Divide the supernatant in half and test each half with the remaining cobalt (II) nitrate and sodium phosphate solutions.

Part II. Into 3 beakers measure 20.0 mL of stock cobalt (II) nitrate solution. Measure various amounts of stock sodium phosphate into each beaker. The suggested amts are: 4.0, 12.0 and 20.0 mL or 8.0, 16.0 and 24.0 mL. Mix each solution thoroughly and allow to stand for at least 10 minutes. Label and weigh 3 sheets of filter paper. Mix and filter each of the reaction mixtures. Catch the 1st 15-20 mL of supernatant and set aside in separate, clean and labeled beakers. Wash each precipitate with 2 5-mL portions of water. Transfer any remaining ppt to the original filter paper. Dry the filtrates at 110oC for a min of 20 hrs. Let cool and weigh.

Part III. Describe the appearance of each of the supernatants. Divide the supernatants into 2 parts. Test 1 part w/ a dropperful of cobalt (II) nitrate and the other w/ a dropperful of sodium phosphate solution. Explain the results of this testing. What patterns are shown in the mass data? Graph the mass of sodium phosphate against the mass of the ppt and explain what is happening in each section of the curve. Do you feel the supernatant and mass data are evidence for or against the equation you have proposed?


Errata: I teach physical science; General Chem I and II for Level 1 students; Applied Chemistry for Level 2 students which will be teaching from a forensic chemistry point of view; and Food Science. I think my initial approach will be to begin greening 1 lab for each course during 2008-2009 and taking it from there.

Mascenic Regional High School
Department of Science
L-1 General Chemistry
Fall 2008

General Chemistry I Syllabus
Instructor: Judith E. Sidileau
Classroom: Room 111
Office Hours: 2:18-3:00 pm MTuTh or by appointment
Email: jsidileau@mascenic.org
Hours per Week of: Lecture 4.5 hr Laboratory 3 hr

Catalog Description: Semester I of a two-semester sequence in chemistry that presents fundamentals of atomic theory and molecular structure, chemical bonding, and the chemical and physical behavior of metals, nonmetals, and their compounds. Laws and concepts of chemistry, including elements, atomic structure, the periodic table, chemical bonding, compounds, chemical equations, and stoichiometry are presented. Laboratories are used to reinforce lecture content as well as to develop critical inquiry skills and laboratory methodology. With General Chemistry II is intended to provide a solid grounding representative of the first year of college-level chemistry. (Prerequisite: a grade of B or better in L-1 physical science and L-1 biology; high school algebra II or beyond.)

Required Texts: Chemistry, The Central Science by Brown, LeMay, Bursten – 12th edition.
Lecture Outline by J.E. Sidileau
Inquiries Into Chemistry, by Abraham Pavelich, 3rd edition, 1999,
Waveland Press.

Grading Policy: 4 hour exams @ 100 pt each = 400 points
4 problem sets @ 25 points each = 100 points
laboratory = 250 points
final exam = 250 points
total points = 1000 points

Course Objectives:
Students who successfully complete this course should be able to:

1. Know the atomic symbols for the common elements.
2. Distinguish between an element, compound, and a mixture based upon (a) physical and
chemical properties and (b) atomic and molecular properties.
3. Express any number expressed in decimal format to the same number expressed in
standard scientific notation and vice versa.
4. Determine the number of significant figures in a number and determine the number of
significant figures that arise after a mathematical calculation involving multiplication,
division, addition, and subtraction.
5. Convert a measurement from one set of units into another.
6. Given any two of the variables mass, volume, and density, determine the third variable.
Be able to predict the properties of materials based upon their densities.
7. Define the three states of matter based upon their physical properties and predict the
physical state observed under normal conditions for any element, including whether
the element is diatomic.
8. Describe the experimental results and conclusions associated with:
a. Rutherford's gold foil experiment.
b. Thomson's cathode ray experiment.
9. Know the charges and relative sizes of subatomic particles and determine the number
of protons, neutrons, and electrons contained in an atom or ion of a specific isotope of
an element given its atomic symbol.
10. Given the periodic table and the symbol for an element, be able to identify:
a. the likely monoatomic ion that it will form in binary salts.
b. its chemical reactivity.
c. its metal/metalloid/nonmetal character.
11. Write the names and formulas of simple binary ionic compounds and ionic
compounds containing polyatomic ions.
12. Calculate the molar mass of a compound and covert between the number of grams of a
compound or element, moles of that substance, and the number of molecules or atoms.
13. Calculate a compound's percent composition given the formula of the compound or
vice versa.
14. Write a balanced chemical equation from a verbal description of a simple chemical
reaction.
15. Calculate the amount of product from given amounts of several reactants and identify
the limiting reagent. Calculate the amount of excess reactant remaining.
16. Calculate the molarity of a solution made by dissolving a solid or diluting a more
concentrated solution.
17. Predict whether or not a salt is soluble in water. Predict the species in solution for a
pure salt, strong acid, or strong base dissolved in water.
18. Predict the products for an acid-base reaction and write a balanced chemical equation
for the reaction.
19. For gases:
a. Given three of the following four variables n, P, V, T, be able to predict the fourth
variable using the ideal gas law.
b. Given the initial state of a gas and its conditions (n, P, V, T) and a set of changes in
some of the conditions, calculate the final state of the gas.
c. Use the ideal gas law to calculate molar mass or density of a gas.
d. Use Dalton's Law to predict pressure of gases in a mixture.
e. Use Graham's Law to calculate the molar mass of a gas or its rate of effusion.
f. Be able to differentiate conditions under which gases deviate from ideality.
20. Given any three quantities of heat, mass, specific heat, and temperature change,
perform numerical calculations to determine the fourth quantity.
21. Know the sign conversions for heat and work and know the meaning of endothermic
and exothermic.
22. Calculate ΔH for a chemical reaction given tables containing enthalpies of formation
for the reactants and products.
23. Describe the essential components of Dalton's atomic theory and compare and contrast
Dalton's atomic theory with modern quantum theory based on quantum mechanics.
24. Convert between wavelength, frequency, and energy of electromagnetic radiation and
predict the relative wavelength or frequency of different types of electromagnetic
radiation.
25. Know the quantum numbers used to identify main levels, sublevels, and individual
orbitals for electrons in an atom. Know the electron capacities of main levels,
sublevels, and orbitals.
26. Write the electronic configurations for an atom or ion given its atomic symbol.
27. Apply Hund's Rule or Pauli's Exclusion Principle to draw an orbital diagram for an
atom or ion.
28. Given the formula of a molecule or ion predict the Lewis dot structure.
29. Predict results for simple experiments pertaining to the objectives above and perform
experiments to test these predictions. Formulate hypotheses to explain experimental
results.
30. Demonstrate proficiency with basic laboratory skills used in chemistry to achieve a
specific goal, e.g. determining the concentration of an unknown solution, etc.
31. Calculate the empirical formula of a substance given results from elemental analysis.
Be able to determine molecular formula of the compound from elemental analysis and
mass spectrophotometry results.
32. Determine oxidation number of any element in a compound.
33. Balance oxidation-reduction reactions in both acidic and basic solutions.
34. Calculate the volume of a gas produced from a given amount of solid reactant given
pertinent P and T data.
35. Use periodic trends to predict patterns of reactivity.
36. Determine heat flow with change of state.
37. Understand the octet rule and know its exceptions.
38. Use VSEPR theory to predict molecular geometry as well as the shape and polarity of
molecules.
39. Determine the hybridization of molecular orbitals and give the number of σ and π
bonds in any molecule.
40. Calculate mole fractions of a mixture of gases.
41. Differentiate the different intermolecular forces.
42. Draw and interpret phase diagrams.
43. Calculate the thermodynamics of phase change, including heats of vaporization and
fusion.

Attendance Policy: Regular class attendance is obligatory. As per the student handbook, "Any student who has more than 10 unexcused absences during a semester will lose one percentage point off their final average for every day, to a maximum of 20 percentage points." Therefore, no makeup work shall be given nor extensions granted under any circumstances due to failure to attend regularly-scheduled classes unless the absence has been excused by the office.

Problem Sets: Four problem sets will be handed out over the course of the semester. You will have exactly one week from the time they are handed out to complete them. You will not be able to work with other students, nor to seek help from anyone else on these problem sets. There will be no make-up problem sets given.

Hour Exams: There will be no make-up exams given for any unexcused absences.

Final Exam: The final exam will be comprehensive. You must take the final exam in order to receive a passing grade for this course.

General Information:

1. It is inappropriate and disruptive to enter the classroom late or to leave early. If you are late or must
leave early, please sit in the back of the classroom. Do not talk to your friends during lecture. All cell
phones must be turned off. It is to everyone's advantage to have the lecture room quiet during class.

2. Written homework is assigned for each chapter, but will not count toward your final grade. Answers
to the problems will be posted. Do the homework, review your lecture notes, and read the text before
coming to class.

3. Four hourly exams will be given during class time on regularly-scheduled days. Any missed exam
will be recorded as a zero. There will be no make-up exams for unexcused absences. Make-up exams
will not be in the same format as the regularly-scheduled exam.

4. Cheating will not be tolerated. This includes problem sets, copying lab reports falsifying data, and
exams. The district policy on cheating is described in the student handbook. In the case of cheating,
the minimum penalty will be a grade of 0 for that assessment.

5. Please note that this is a relatively fast-paced course. A tentative outline of the course is provided. It
is my intent to follow that schedule as closely as possible. therefore, not all material in every chapter
may be presented in lecture. You will be expected to cover some of the material on your own. It is in
your best interest to stay on top of the lecture material and attend class regularly. If you have
difficulty with the material, discuss your situation with me as problems arise; not the morning of, or
the week after, the exam.

6. You must successfully complete the laboratory with a passing grade of 60 percent or above in order to
receive a passing grade for this course.

7. The Lecture Outline is a workbook that contains partial notes for the course. It is designed to reduce
the amount of note-taking and allow for greater participation and attention during lecture.

8. Contacts are not permitted in the laboratory. Safety goggles is mandatory during lab.

9. Laboratory reports must be turned in one week following completion of the work. Your report will be
returned to you within one week of it being submitted. Reports will be worth 10 points each. The total
grade will be normalized to 250 points at the end of the term. There is a penalty for labs that are
submitted late.

Grades:

94-100 A 84-86 B 74-76 C 64-66 D
90-93 A- 80-83 B- 70-73 C- 60-63 D-
87-89 B+ 77-79 C+ 67-69 D+ 0-59 F


Lecture Material:

WEEK LECTURE EXPERIMENT

1 Introduction: Matter and Measurement Introduction/Lab Safety

2 Atoms, Molecules, and Ions Uncertainty in Measurements

3 Stoichiometry: Calculations with Chemical Physical Relationships
Formulas and Ions

4 Stoichiometry Hydrates

5 Aqueous Reactions and Solution Spectral Analysis for Cu2+
Stoichiometry

6 Solution Stoichiometry Precipitates

7 Gases Acid and Base Classifications

8 Gases Pressure, Volume, Temperature
Relationships

9 Electronic Structure of Atoms Chemical Properties

10 Electronic Structure of Atoms Flame Tests

11 Periodic Properties of the Elements Titration of Fruit Juices

12 Basic Concepts of Chemical Bonding Acetylsalicylic Acid

13 Basic Concepts of Chemical Bonding Saponification

14 Thermochemistry Dissolution Reactions

15 Thermochemistry KOH and HCl

16 Molecular Geometry and Bonding Theories Molecular Structures
17 Molecular Geometry Molecular Models on a Computer

18 Intermolecular Forces, Liquids, Solids Designing a Snowflake

19 Nuclear Chemistry "A Penny For Your Neutron"

20 Review and Final Lab Practicum

Rubric for Laboratory Reports
Scientific Method Level 4 Level 3 Level 2 Level 1
Question for Investigation Appropriate and fully stated in correct terms Appropriate and fairly well-written Somewhat workable, is poorly stated, or is incomplete Unclear or unworkable
Hypothesis Well-written, fully stated in clear terms with a good explanation or justification Acceptable; justification or explanation is good Weak or unclear; no explanation or justification is given Illogical or does not apply to the investigation
Procedure Very good; fully explained; includes steps, materials, and variables; easy to understand what the student did and how it was done Good; workable; most of the steps, materials, and variables are included Sketchy; somewhat workable; important steps, materials, and variables are not included No steps listed or is totally unworkable
Observations and Results Recorded and organized into charts, graphs, sketches, etc. that are complete and easy to read; results are well-summarized in a written statement Recorded and organized well; results are summarized Partially recorded and/or organized ineffectively; results are not summarized Not recorded in an acceptable manner; not organized in any way
Conclusions Logical and well-stated with a good comparison of the results to the original hypothesis; clearly the student learned something Fairly well-stated and acceptable comparisons between results and hypothesis Present and fairly logical, but not well-explained; no comparison of results with hypothesis Totally illogical or not supported by the investigation
Mechanics of Writing Work is legible and in final copy form; follows writing conventions (punctuation, capitalization, spelling, and grammar) Errors are few and do not interfere with the communication and understanding of concepts Several errors are made that interfere with the communication and understanding of concepts Multiple errors are made that interfere with the communication and understanding of concepts.

New Ideas:
1. Replace cobalt with a copper (II) salt and phosphate with hydroxide. A ppt is still formed and LR may still be determined visually in the supernatant.
2. Green experiment by recycling the copper metal from the copper (II) hydroxide formed. New experiment follows.

PRECIPITATES

Part I. Qualitative Properties of Copper (II) Sulfate-Potassium Hydroxide Interactions.

A. Dissolve a small amount (~1cm3) of solid copper (II) sulfate in about 20 mL of distilled water. Dissolve a similar amount of solid potassium hydroxide in a second 20 mL portion of water. Describe the appearance of each solution.
B. Pour half of each solution into a third beaker and mix thoroughly. (Save the mixture and two solutions for later use.)
1. Describe the appearance of the mixture.
2. Assuming the reaction involves the coming together of dissolved ions, what are the possible identities of the solid formed in the mixture? Think up and carry out experiments which would distinguish among all of the possibilities. Describe the results of these experiments.
3. Write a chemical equation which represents the reaction and is consistent with the data obtained so far. Briefly explain your reasoning.
C. Separate the mixture by filtration. Note the characteristics of the liquid, called the supernatant, and predict all of the materials which might be dissolved in the liquid.
D. Divide the supernatant in half and test each half with the remaining copper (II) sulfate and potassium hydroxide solutions. Describe the results.
E. What conclusions can be drawn from these data concerning the ions present in the supernatant? (e.g., how might changing the original amounts of copper (II) sulfate and potassium hydroxide affect the ions present in the supernatant?)

Part II. Quantitative Properties of the Copper (II) Sulfate-Potassium Hydroxide Interactions.
A. Clean and distilled water rinse three 100 mL beakers and label them 1-3. Into each beaker carefully measure 20.0 mL of stock copper (II) sulfate solution. (Be sure to record the exact concentration on the label.)
B. Measure various amounts of stock potassium hydroxide into each beaker. The suggested amounts are:

Group 1: 4.0, 12.0 and 20.0 mL, respectively
Group 2: 8.0, 16.0, and 24.0 mL, respectively

C. Mix each solution thoroughly and allow it to stand for at least 10 minutes. Calculate the masses of salts added to each beaker and record these amounts in the table.
D. Label and weigh three sheets of filter paper, recording their masses in the table. Mix and filter each of the three reaction mixtures. Catch the first 15-20 mL of supernatant from each filtration in separate, clean, and labeled beakers. Set aside for later analysis in Part IIIA.
E. Continue the filtrations into any convenient containers. Then wash each precipitate with two 5 mL portions of water, Use these water washes to transfer any precipitate remaining in the original beakers to the filter paper. (These washings will proceed slowly. During this time you can run the tests in Part IIIA. On the supernatants you saved.)
F. After the washings, put the filter papers with their filtrates in labeled beakers and then in an 110oC drying oven. Dry the filtrates for 20 hr or more. Let cool and weigh. Record the data in the table. Collect data from the other members of the class.

Part III. A. Describe the appearance of each of your supernatants. Divide each of the supernatants into two parts. Test each part with a dropper full of copper (II) sulfate and the other with a dropper full of potassium hydroxide solution. Summarize the results of these tests.
B. Explain the results of this testing of the supernatants. What do these results show must have happened in each reaction mixture? (For example, why can you form more precipitate from a supernatant? Why don’t all three supernatants give the same results? Could you have predicted these results from your balanced equation and masses of salts added?)

Part IV.A. What patterns are shown in the mass data? Graph the mass of potassium hydroxide against the mass of precipitate and explain what is occurring in each section of the curve. How does this fit what you would predict the mass of the precipitates to be?
B. In Part I.B. you proposed an equation for the reaction you observed. Do you feel the supernatant and mass data are evidence for or against your equation being correct? Briefly explain your reasoning.




Data Table
(All masses in grams)
Concentration of stock potassium hydroxide solution:
Concentration of stock copper (II) sulfate solution: __
Solution
mL Stock KOH
mL Stock CuSO4
g KOH
g CuSO4
Mass of Paper
Mass of ppt and Paper
Mass of ppt.
1








2








3









Other Student Data:
Solution
mL Stock KOH
mL Stock CuSO4
g KOH
g CuSO4
Mass of Paper
Mass of ppt and Paper
Mass of ppt.
1








2








3








Solution
mL Stock KOH
mL Stock CuSO4
g KOH
g CuSO4
Mass of Paper
Mass of ppt and Paper
Mass of ppt.
1








2








3












Recycling Copper

1. Scrape precipitate into a beaker. Place beaker on a hot plate (low heat setting). If ‘bumping occurs, remove from the hot plate.
2. Allow to heat until solid turns black throughout. Add 40 mL of very hot water to wash the solid and decant off the wash liquid.
3. Add 20 mL of 6 M H2SO4 to the washed solid. If necessary, add a little heat and a few more drops of acid to speed dissolution of the solid.
4. Working in the hood, add a small piece of aluminum foil to the products of the above reaction. Add 2 mL of concentrated HCl. Add more small pieces of aluminum foil, only if necessary, until the reaction is complete.
5. There should be no aluminum foil in your beaker at this point. If there is add 1 mL of concentrated HCl to your beaker.
6. Decant the liquid. Save the entire solid product.Add a few mL of distilled water to wash the product in the beaker. Decant liquid and repeat the water wash.
7. Working in the hood, wash solid with 30 mL of methanol. Decant the liquid after each wash.
8. Dry the product on a hot plate at a low setting. Obtain the mass of dry copper. Place in recovery container.

Summary of Student Results

Two lab sections of sixteen (16) students each performed this experiment this experiment Semester I. The results were as expected and the majority of students, working in pairs, got results that were reproducible by other students in both sections. In one class only 1 group had spurious results, which I atributed to careless measurement of reagents. A graph of class data (Mass of ppt vs mass of copper (II) ion added) for both sections showed remainder of data was reproducible. The graph showed an initial upward trend of increasing slope, indicating hydroxide) ion was the limiting reagent for 4.0 ml, 8.0 mL, and 12.0 mL of potassium hydroxide added. At 16.0 mL, 20.0 mL, and 24.0 mL of hydroxide ion added, the slope leveled off to zero indicating copper (II) ion has become the limiting reagent. Students were able to make a connection using the visual color of the supernatant during filtration to corroborate this. Some students went back and calculated at what volume of added potassium hydroxide this should occur and were able to verify this point on their graphs. Other students merely extrapolated this point from the two curves on their graph. Within reasonable experimental error (10 percent) the students were accurately able to determine this point.

Students took their mass data and calculated the amount of moles of copper (II) ion as limiting reagent and/or hydroxide ion as limiting reagent and graph vs moles of ppt. They used the slope to indicate the mole ratio of each ion in the ppt in an effort to physically corroborate the identity of the ppt as copper (II) hydroxide. Students who did this saw a slope of 1.87 for their hydroxide data and a slope of 1.06 for the copper (II) ion.

Other students performed mass percent calculations in lieu of this second graph. Again, the data was conclusive relative to the identity of the ppt.

I concluded the lab was successful for each of the learning objectives. In addition, the students liked the idea that they were performing an experiment that was more environmentally green than their predecessors has performed. The students enjoyed the classroom visits of the UNH students.

The copper recycling part of the experiment was not, in fact, able to be performed by the students at this juncture in its entirety due to the intervening ice storm and our loss of 9 days of school just before the Christmas break. Instead, two of my students who are currently performing independent research with me are examining this cycle in more detail. Their final papers will be due to me in one month. I, however, did perform the cycle on the students' waste and was able to recover 78.6% of the copper metal, based upon initial mass of the precipitate. I suspect this recovery could easily be improved upon, as I performed this in some haste and in small batches. Using vacuum filtration would also help.