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Ch 312 - Quantitative Analysis, Winter 2012

quant_student.jpg (10159 bytes) A classic course in modern Chemical Analysis including statistics, equilibrium, acid-base theory, titrations, electrodes & potentiometry, UV-Vis spectrophotometry, Atomic Absorption Spectrometry, and Gas Chromatography.

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Learning Outcomes:

  • General Steps in a Chemical Analysis, SI Units and Prefixes, Conversion Between Units, Chemical Concentrations, Preparing Solutions

  • The Analytical Balance, Burets, Volumetric Flasks, and Pipets

  • Significant Figures, Significant Figures in Arithmetic, Types of Errors, Propagation of Uncertainty

  • The Gaussian Distribution, Student's t, Q (Grubbs) Test for an Outlier, Finding the "Best" Straight Line, Constructing a Calibration Curve

  • Principles of Volumetric Analysis, Titration Calculations

  • Precipitation Titrations - Mohr, Volhard, and Fajans

  • Precipitation, Examples of Gravimetric Calculations

  • What Are Acids and Bases? Relation Between [H+], [OH-], and pH, Strengths of Acids and Bases, pH of Strong Acids and Bases, Tools for Dealing with Weak Acids and Bases, Weak-Acid Equilibrium, Weak-Base Equilibrium

  • The Henderson-Hasselbalch Equation, A Buffer in Action, Preparing Buffers, Buffer Capacity, How Acid-Base Indicators Work

  • Titration of Strong Base with Strong Acid, Titration of Weak Acid with Strong Base, Finding the End Point
    Finding the pH in Diprotic Systems, Titrations in Polyprotic Systems

  • The Effect of Ionic Strength on Solubility of Salts, Activity Coefficients, Charge and Mass Balances , Systematic Treatment of Equilibrium

  • Fractional Composition Equations, Metal-Chelate Complexes, EDTA, Metal Ion Indicators, EDTA Titration Techniques, The pH-Dependent Metal-EDTA Equilibrium, EDTA Titration Curves

  • Redox Chemistry and Electricity, Galvanic Cells, Standard Potentials, The Nernst Equation, E° and the Equilibrium Constant

  • Reference Electrodes, The Silver Indicator Electrode, The Calomel Electrode, How Ion-Selective Electrodes Work, pH Measurement with a Glass Electrode, Ion-Selective Electrodes, Theory of Redox Titrations, Redox Indicators

  • Properties of Light, Absorption of Light, Using Beer's Law, The Spectrophotometer, Analysis of a Mixture

  • What is Atomic Spectroscopy? Atomization, How Temperature Affects Atomic Spectroscopy, Instrumentation

  • What is Chromatography? How We Describe a Chromatogram, Why Do Bands Spread?, Gas Chromatography
Instructor:
Dr. Pete Poston
office: NS 110
phone: 503-838-8218
office hours: MWF 2 and 4, make an appointment, or just drop by.
web page: http://www.wou.edu/poston
email questions: postonp@wou.edu
Pre-req's
Ch 223
Textbook
"Exploring Chemical Analysis" by Harris, 4th ed.
NOTE: the homework questions come from the 3rd ed, and are availalbe on eReserve
Cell Phones and Computers

I have mixed feelings about smart devices - they can be a valuable educational resource, but texting, etc is discouraged. What's the point to coming to class if you aren't paying attention?

However, from time to time I will recommend interesting, educational, and fun app's and will use them in lectures and during the recitation. Feel free to download them at that time.

Cell phones need to be either turned off or placed in vibrate mode during lecture. If I see you using one of these devices during testing, I will consider it cheating and give you a zero.

Calculators
A scientific calculator is mandatory. You must come prepared for every quiz, midterm, and final with your own calculator. You are not allowed to borrow one from another student while testing, and you may not use your cell phone as a calculator
Homework
Homework will be assigned and posted, but not graded. Usually a homework problem or a problem covered in lecture makes it on an exam!
Lab

I will furnish the lab manual; also, you will need to purchase a bound lab notebook from the bookstore. I will be checking and grading your notebooks at unannounced times! To save yourself time, outline the procedure from the manual into your notebook before coming to lab. BE PREPARED BEFORE ENTERING THE LAB!

The results of titration labs will be turned in on a 3 X 5 filecard with the same format as shown on the attached page. Your results must be accurate to within 5 parts-per-thousand (0.5%)! For example, if the percent purity of an unknown is 46.36% and your average value is 46.71%, then you are OK.

Every lab is due at the beginning of the following week's lab. Late labs lose 25% per day.

If you miss two labs, you fail the course! Also, if you don't turn in a lab notebook you fail the course.

Exam and Lab Policies

There are no make-up exams except for University sanctioned events, in which case please see me a week in advance for an alternative testing time.

In the event of an unexpected emergency, then -

Midterms: Family-related emergencies or deaths must be communicated through the Office of Student Affairs (838-8221) and broadcast to all your professors. Illnesses must be verifiable. Under these conditions I will replace the missing hour exam score by taking 30% of the percentage you receive on the final exam (since it is a 200 pt exam) and 40% of the other midterm score. This option can obviously only be used once.

Final exam: University policy states that the final exam time will not be moved. Please do not ask to take the final early because you want to leave for vacation early! There are humanitarian exceptions - see me if there's a problem. Again, if you miss the final and follow the same procedure listed above under midterms, then I will give you an incomplete and you can take the final in a future class section to make it up (see Incompletes section below)

Lab: there are no make-up labs, so if you miss one, follow the procedures above. I will replace your missing lab with the average of your others

Grading
2 midterms (Tue, Jan 31 and Tue, Feb 28) 200 points (34 %)
Final - weighted towards final chapters (R Mar 22, 8-10 AM) 200 points (34 %)
Lab: first 6 labs at 20 pts; last 3 labs at 10 pts, buffer exercise 10 pts 160 points (27 %)
Lab notebook 25 points (4 %)
Total 585 points
Incompletes

Incompletes are given under special circumstances such as medical reasons, family emergencies, etc. In order to receive an incomplete, the University requires you to sign a contract with me outlining the steps you must take to finish the course. Usually this means there will be a time deadline for completion of the course before your grade reverts to an "F".

Students with Disabilities

It is your right to request special accommodations under the Americans with Disabilities Act. For questions, call the Office for Disability Services at (503) 838-8250 V/TTY, or email them at ods@wou.edu.

The Code of Student Responsibility defines cheating as "intentional use, or attempted use of artifice, deception, fraud, and/or misrepresentation of one's academic work". For this class, which involves taking exams, quizzes, and perform labs, cheating is usually but not limited to talking or writing to other students, using crib sheets (prepared notes), or looking at another student's paper. The penalty for cheating will be a zero grade for the test or quiz or assignment in question.

Students have the right to appeal this action as described in the Code of Student Responsibility


COURSE OUTLINE

Reading, problems, and Labs will be periodically updated

*AY stands for "Ask Yourself" problems found in the text.
**Fri, Feb 11th is the last day to drop without being responsible for a grade

Week of Tuesday... Chapter Reading/
Homework Problems
(from 3rd ed of the text)
Lecture Topics Lab
Jan 10

reading:
Ch 0: p. 1-10
Ch 1: p. 19-36
Ch 3: p. 61-73
Ch 4: p. 83-96
Ch 6: p. 127-132
Ch 7: p. 151-164

problems (SET 1):
Ch 1: 3, 15, 22, 25, 26
Ch 2: 6
Ch 3: 1, 4(a-e), 13(c), AY 3-C (p.58)
Ch 4: 2, 4, 5, 13, AY 4-D (p.82)
Ch 6 (PART 1): 1, 4, 9, AY 6-A(c) (p.111)
Ch 7: 3, 6, AY 7-B (p.140)

Ch 0 - The Analytical Process
Ch 1 - Chemical Measurements
Ch 3 - Math Toolkit
Ch 4 - Statistics
Ch 6 - Good Titrations
Ch 7 - Gravimetric & Combustion Analysis

Check-in

Mini-lecture Ch 2 "Tools of the Trade" on basic lab techniques and equipment

LAB #1 -Statistics Using Microsoft Excel

Jan 17

reading:
Ch 6: p. 136-140
Ch 8: p. 171-190
Ch 9: p. 195-206

problems (SET 2):
Ch 6 (PART 2): 19, 20
Ch 8: 1, 4, 7, 8, 14, 16, 19, 29
Ch 9: 1, 6, 10(a-c), 20

Ch 8 - Introducing Acids & Bases
Ch 9 - Buffers
Ch 6 - Good Titrations (Sec 6-4 on Ksp)

LAB #2 - Neutralization Titration of KHP

Jan 24

reading:
Ch 9: p. 206-210
Ch 10: 213-228
Ch 12: 265-277

problems (SET 3):
Ch 12: 9, 10(a), 15, 16, 22, 27
Ch 10: 2, 6, 8, 15, 20, 25

Ch 12 - A Deeper Look at Chemical Equilibrium
Ch 10 - Acid-Base Titrations

LAB #3 - Potentiometric Titration of Soda Ash
(illustration of equilibrium & titration curves)

spreadsheet analysis of titration data

Jan 31*

reading:
Ch 11: p. 239-259

problems (SET 4):
Ch 11: 1, 3, 4, 9, 15, 21(b), 25, 26

Ch 11 - Polyprotic Acids & Bases

EXAM #1 - Tue, Jan 31

LAB #4 - Precipitation Titration
Feb 7

reading:
Ch 13: p. 287-304
Ch 6: p. 140-145

problems (SET 5):
Ch 13: 9, 18, 19acde
Ch 6 (PART 3): AY 6-E (p.123), AY 6-F (p. 126)

Ch 13 - EDTA Titrations
Ch 6 - Good Titrations (Precipitation Titrations)

LAB #6 - EDTA Titrations
Feb 14

reading:
Ch 14: p. 309-326
Ch 16: p. 357-364

problems (SET 6):
Ch 6 (PART 4): 2, 3
Ch 14 (PART 1): 2(a), 6, 10(a), 13
Ch 16: 6 and 8 (eq. pt. only)

Ch 14 - Electrode Potentials (Electrochemistry Review - Sec. 14-1-14-5)
Ch 16 - Redox Titrations (Sec. 16-1-16-2)

LAB #7 - Determination of Iron in Iron Ore

Feb 21

reading:
Ch 14: p. 327-329
Ch 10:
p. 222-227
Ch 15:
p. 339-353

problems (SET 7):
Ch 14 (PART 2): 21
Ch 10: 25
Ch 15: AY 15-D (p. 323)

Ch 14 - Electrode Potentials (Reference Electrodes - Sec. 14-6)
Ch 10 - Acid-Base Titrations - Finding the End Point Potentiometrically (Sec. 10-4)
Ch 15 - Electrode Measurements

Buffer exercise
Feb 28

reading:
Ch 18:
p. 393-402, 404-410
Ch 19: p. 415-423

problems (SET 8):
Ch 18: 6, 8, 14, 16, 22
Ch 19: 1, 2, 6

EXAM #2 - Tue, Feb 28

Ch 18 - Let There be Light
Ch 19 - Spectrophotometry: Instruments & Applications

LAB #8 - Spectrophotometric Analysis of a Mixture: Caffeine and Benzoic Acid in a Soft Drink

Mar 6

reading:
Ch 20:
p. 441-443, 448-452

problems (SET 9):
Ch 20: AY 20-E (p. 440)

Ch 20 - Atomic Spectroscopy

LAB #9 - The Determination of Lead in Brass by Atomic Absorption Spectroscopy (AAS)
Mar 13

reading:
Ch 21:
p. 459-469
Ch 22: p. 481-488

problems (SET 10):
Ch 21: 2, 8, 12, 15
Ch 22: 1, 2, 4(a)

Ch 21 - Principles of Chromatography & Mass Spectrometry
Ch 22 - Gas & Liquid Chromatography

LAB #10 - Quantitative Gas Chromatography (GC) of Alkanes

*Friday, Feb 3 is the last day for dropping a course(s) or withdrawing from school without being responsible for a grade(s)

 

I grade notebooks based upon the following criteria:

  1. pages numbered
  2. notebook bound
  3. table of contents
  4. presence of any loose papers
  5. written in pen, not pencil
  6. errors crossed out, not blacked out
  7. overall organization
  8. usage of significant figures
  9. neatness and legibility
  10. record of each step in an analysis written down

These guidelines are meant to provide legal protection for any scientific discoveries made (patent rights), to locate procedural errors, or to protect a company in the event a customer has any complaints. TAKE THE LAB NOTEBOOK VERY SERIOUSLY!

Turn in titration lab results on a 3 X 5 file card with this format:

Name ____________________     Date _______________________
Unknown # _______________      Lab _______________________
Molarity of solutions:
          wt sample                    mL titrant                    % purity                
trial 1
trial 2    <-----------     (use 4 significant digits)   ---------------->
trial 3

true mean = xx.xx % ts/sqrt(N)

relative standard deviation =


TITRATION TIPS

  1. Make sure that there is no air bubble in the buret tip. If there is a bubble, remove it by dispensing a few milliliters of titrant.
  2. You can always get 4 significant digits out of a buret (unless the volume is less than 10.00 mL).
  3. Always read the bottom of the meniscus. Hold a card with a black spot on it behind the meniscus in order to read it clearly. Hold your eye level with the meniscus in order to avoid parallax errors.
  4. NEVER attempt to fill the buret to exactly 0.00 mL, you cannot do it! Instead, fill it close to 0.00 mL and estimate the volume.
  5. 1 drop = 0.050 mL. Use this if you reach the endpoint and you have a drop stuck on the tip of your buret.
  6. You can add less than a drop of titrant if you let it stick to the tip, and then rinse it off with a bottle of distilled water.
  7. Obtain a heat-stir plate for your titration if available. Use the stirring option while titrating.
  8. Sometimes analyte splatters onto the side of the flask during the titration. Periodically rinse it off with distilled water.

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