WELCOME! ELEMENTARY QUANTITATIVE ANALYSIS CHEM 221

1. WELCOME! ELEMENTARY QUANTITATIVE ANALYSIS CHEM 221

2. ELEMENTARY QUANTITATIVE ANALYSIS • CHEM 221, Fall 2007 • Tues & Thur 9:30-10:45, Rm. 112 Hamilton Hall • COURSE OUTLINE • Instructor: Dr. Robert Powers • OfficeLabs • Address: 722 HaH 720-721 HaH • Phone: 472-3039 472-5316 • e-mail:rpowers3@unl.edu • web page: http://bionmr-c1.unl.edu/ • Office Hours: 10:30-11:30 am MWF or by Special Appointment • I am in my office many other times during the week and am always • willing to speak with you if you find me in or make an appointment. • Teaching Assistants: • Ms. Jennifer Copeland phone: 472-5316 office: 721 HaH • Ms. Kelly Mercier phone: 472-5316 office: 721 HaH • Mr. Rob Waters contact: Resource center e-mail: bor9455@hotmail.com

3. COURSE OUTLINE • Required Items: • (i)Chem. 110 is the only prerequisite • (ii)Text: "Quantitative Analysis" 7/e Daniel C. Harris, Freeman & Co., New York • (iii) Lab Manual: "Laboratory Manual for Quantitative Chemical Analysis", J.D.Carr (2007) • Laboratory Notebook: bound (not spiral), use one with grids instead of lined pages for graphs. • (vi) Black Sharpie for labeling glassware • (vii) Calculator for exams and lab (TI-89 style or a simpler model) • (viii) Laptop (optional) to run Excel calculations during lab Course Work: Exam 1: 100 pts (Thurs., Sept. 20) Exam 2: 100 pts (Thurs., Oct. 18) Exam 3: 100 pts (Tues., Nov. 20) Final: 200 pts (10am-12pm, Wednesday, Dec. 19) Laboratory: 400 pts (due at end of each lab) Lab Notebook: 100 pts (due at end of semester) Total: 1000 pts Homework problem sets will not be collected or graded, but will aid your preparation for the exams.

4. Lecture Topics Date Chapter Topic Problems Aug 28 Chap 0 & 1 Measurement 0-1,5-A,6 & 1-5,7,22,24,26 Aug 30 Chap 2 & 3 Tools 2-D,1,10,15, & 3-A,5,9,11 Sept 4 Chap 3 Error 3-12,13,15,18,21,23 Sept 6 Chap 27 Gravimetry 27-2,3,7,14,18,25,26 Sept 11 Chap 4 Statistics 4-B,E,2,3,6 Sept 13 Chap 4 Statistics (cont) 4-9,11,13,14,15,18,22 Sept 18 Chap 5 Calibration 5-A,B,C,22,23 Sept 20 EXAM 1 Sept 25 Chap 6 Equilibrium (Intro) 6-A,B,G,I,K,1,2,3,5,13 Sept 27 Chap 6 Equilibrium (cont) 6-17,21,37,40,54 Oct 2 Chap 7 Titrations 7-B,C,D,1,2,4,8,11,13 Oct 4 Chap 8 Activity 8-A,C,1,4,8,14 Oct 9 Chap 8 Equilibrium (systematic) 8-F,G, H,10,16 Oct 11 Chap 8 Equilibrium (more) 8-18,8-21,8-23 Oct 16 Chap 8 Equilibrium (even more) 8-26, 28 Oct 18 EXAM 2 Oct 22-23 Fall Break Oct 25 Chap 9 Monoprotic acid/base 9-B,C,G,H,4,6,10,13,19 Oct 30 Chap 9 Monoprotic (again) 9-24,26,27,29,30,36,37 Nov 1 Chap 10 Polyprotic acid/base 10-A,1,2,4,7,9,16,23,29,31,33,38 Nov 6 Chap 11 Acid/base Titrations 11-A,B,F,G,I,3,5,6,7,13,16 Nov 8 Chap 11 Acid/base Titrations (cont) 11-23,27,34,36,45,46,54,64 Nov 13 Chap 12 EDTA Titrations 12-B,2,4,5,6,13,22,28 Nov 15 Chap 14 Electrochemistry 14-B,D,I,2,3,15,18,25,41 Nov 20 EXAM 3 Nov 22-23 Thanksgiving Nov 27 Chap 15 Potentiometry 15-E,6,7,8,10,13,17,23,24 Nov 29 Chap 16 Redox Titrations 16-A,C,1,2,7,14,15,16,24 Dec 4 Chap 18 Spectrophotometry 18-A,C,D,1,6,8,16,18,19 Dec 6 Chap 23 Separations 23-B,1,2,3,29, 44 Dec 11 Chap 23 Separations Dec 13 Chap 24 Gas Chromatography 24-A,B,C Dec 19 FINAL EXAM 10:00-12:00

5. Tentative Lab Schedule Due to equipment limitations, experiments # 7, 10, 11, 14 & 15 will be taken in different order by portions of the students. Scaled to 400 for final grade NOTE: Students having a Monday lab should make up Sept 4 lab on Sept 7 (Friday)

6. COURSE OUTLINE Lectures: ALL PowerPoint lecture notes are available online on BlackBoard and my web-site (http://bionmr-c1.unl.edu/). !!!!The Lectures Notes Are Not Meant To Replace Attending Class!!!!! • Laboratory: • 50% of your grade in CHEM 221 is based on your laboratory effort. • You will be furnished samples whose composition is unknown to you. • You will be asked to determine how much of a given analyte is present. • You will be graded on how well you agree with the correct answer. • You are allowed to re-do one lab during the next to last week • You are allowed to re-submit one lab calculation if you made a math mistake at no • penalty to your lab grade: • you must clearly state what the mistake was and how you corrected it • each subsequent resubmission of a calculation error will incur a progressive 10% penalty • 2nd re-submission -10%, 3rd re-submission -20%, 4th re-submission -30% • You will also be graded on how well you keep and maintain your lab notebook. Good Lab Practice and Techniques are Essential

7. Lab Notebook Techniques • The Lab Notebook Must: • State what was done. • State what was observed • Be understandable to someone else • Include Complete Description of Experiment: • Purpose • Methods • Results • Conclusions • Include Balanced Chemical Equations for Every Reaction Used • Paste Hardcopies of Important Data in Notebook • Include locations Where other Data is stored (computer files) • Notebooks are Legal Documents and Routinely Used for Patent Litigation • Laboratory Notebook should be bound (not spiral), use one with grids instead of lined pages for graphs.

8. Lab Notebook Techniques This Notebook Page is incomplete and a Useless Document. Limited Detail. This Notebook Page Has Precise Description with Adequate Detail

9. How to Read and Use a Buret When reading a buret, it is important that your line of sight be in a direction perpendicular to the buret column. All buret reading should be done using a buret card.

10. How to Read and Use a Buret Upper limit of the black streak ought to be placed just under the meniscus, so that the bottom of the meniscus can be seen distinctly against a narrow zone of white. Read volume associated with bottom of “meniscus”. A 50 mL buret can be read to ±0.01 ml. A constant dark reflection against a white background enables higher precision in determining relative titrant volumes.

11. How to Read and Use a Buret A bubble in the nozzle of a buret will produce an inaccurate volume reading if the bubble escapes during a titration The quickest way to get rid of bubbles is to fill the buret with titrant and open the valve. Some bubbles may require “light” tapping to dislodge them.

12. Microsoft Excel Demo

13. Introduction to Analytical Chemistry Identifying an Unknown Is Not As Easy as Portrayed by the CSI TV Show. Typically Requires More Than One Experiment and > 45 Minutes of Analysis with corresponding high cost (single DNA analysis ~$10,000) CSI: Crime Scene Investigation

14. Introduction to Analytical Chemistry • Background • 1.)Definition: • ANALYTICAL CHEMISTRY: The Science of Chemical Measurements. • 2.)Types of Questions Asked in Analytical Chemistry • a.) What is in the sample? (qualitative analysis) • b.) How much is in the sample? (quantitative analysis) • 3.)Techniques used in Analytical Chemistry: • a.) Wet Chemical Methods: titrations, color-forming reactions, • precipitations, etc. • b.) Instrumental Methods: spectrometry, chromatography, etc. What is it ? How much is there? How pure is it? What are the impurities?

15. Introduction to Analytical Chemistry • The Analytical Process • 1.)Formulating the Question: • Translate General Question into Specific Question • Is this water safe to Drink?  What is the concentration of Arsenic in the water sample? • 2.)Selecting Analytical Procedures: • a.) Choose procedure to measure Arsenic in water • Uncertainty in measurement • Limit of detection • Destroy sample • Availability, time, cost • b.) If necessary, develop new procedure • 3.)Sampling: • a.) Select representative material to analyze (i) don’t use the entire sample (ii) consistency in sample collection

16. Introduction to Analytical Chemistry • The Analytical Process • 4.)Sample Preparation: a.)convert sample into form suitable for chemical analysis • Dissolve sample • Concentrate sample • Remove species that interfere with analysis

17. Introduction to Analytical Chemistry • The Analytical Process • 4.)Sample Preparation: a.)Example: How do you prepare samples for Drug Discovery? • What we want to know: • Is the drug active? Does it cure the disease/illness? • How is the drug taken? (Pill, injection) • How often does the drug need to be taken? • Does the drug have side-effects? • How these Questions are Typically Addressed: • Treat animal (rat, mice, etc) with drug • Monitor drug duration in animal • Monitor location of drug accumulation • Monitor animal health • How do you treat the animal with the drug? • How do you monitor the drug concentration in the • Animal? • How do you determine the drug location? • How do you determine the animals health? Tumor size is measured by fluorescence through the mouse skin using quantum dots as a function drug dosage M. Dahan et al.,Science (2003) 302:442-445

18. Introduction to Analytical Chemistry • The Analytical Process • 4.)Sample Preparation: a.)Example: Cross-section of sacrificed mouse showing tissue removal How do you prepare samples for Drug Discovery? Inject mouse with drug Tissue plug from mouse kidney Determine drug quantity and distribution Chromatography indicates presence of drug an metabolites in tissue sample Regulatory Toxicology and Pharmacology 31, S57–S62 (2000)

19. Introduction to Analytical Chemistry • The Analytical Process • 5.)Analysis: a.)measure concentration of analyte in several identical aliquots (portions) • Replicate measurements  uncertainty in the analysis • Avoid large errors • Reliability of measurement • Calibration Curve • Measure response for known samples 6.) Report and Interpretation of Results 7.) Drawing Conclusions • How the Report is used

20. Units and Concentrations To a large extent, analytical chemistry is a science of measurement and measurements require minimizing errors • Units of Measurement • 1.)SI Units: a.)international units of measurement (metric units) b.)ALL SI units are based on certain fundamental quantities

21. Units and Concentrations Units of Measurement Standards of length were once represented by the distance between two marks on a solid metal bar. Copies of these standards were displayed in public places so that people could check the accuracy of the rules they were using. Standards Of Length (1876) Trafalgar Square In 1588, Elizabeth I issued a new standard yard which remained the legal British yard for over 300 years.

22. Units and Concentrations Units of Measurement History of the meter • Origins of the meter go back to at least the 18th century • Two competing approaches to the definition of a standard unit of length. • define the meter as the length of a pendulum having a half-period of one second • define the meter as one ten-millionth of the length of the earth's meridian along a quadrant • (1791) French Academy of Sciences chose the meridian • force of gravity varies slightly over the surface of the earth, affecting the period of the pendulum. • meter equal 10-7 of the length of the meridian through Paris from pole to the equator. • prototype was short by 0.2 millimeters because researchers miscalculated the flattening of the earth due to its rotation. • (1960) used a definition based upon a wavelength • of krypton-86 radiation • (1983) meter replaced by the following definition: • The meter is the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second. International Prototype Meter standard bar made of platinum-iridium

23. Units and Concentrations Units of Measurement The Saga of Claude Émile Jean-Baptiste Litre • International System of Units uses the character "l" (lower-case L) to denote the metric unit of volume litre (liter). • It is often difficult to distinguish between the character "l" and the digit "1" in certain fonts or when handwritten. • International System of Units only permits the use of a capital letter when the unit is named after a person. Kenneth Woolner of the University of Waterloo perpetuated a hoax in the April 1978 issue of CHEM 13 News • Woolner created the fictional character of Claude Émile Jean-Baptiste Litre with a distinguished scientific career where he purportedly proposed a unit of volume measurement. 1 liter “since no such person existed for "L", it seemed reasonable that one should be invented. Reg suggested that I should write a "biography" for the April issue of CHEM 13 NEWS, and over the course of an evening (which included, I think I recall, most of a bottle of scotch) we generated much of the substance of an 18th century life, full of drama, revolution and romance.” – Dr. Woolner , 1988

24. Units and Concentrations • Units of Measurement • 1.)SI Units: d.) To indicate multiples or fractions of units, various prefixes are used Example: 3.2x10-11 s = 32 x10-12 s = 32 ps

25. Units and Concentrations • Units of Measurement • 1.)SI Units: e.) conversions to SI units f.)Liter is commonly used for volume instead of m3

26. Units and Concentrations • Units of Measurement • 2.)Expressions of Concentration: a.)Molarity (moles/L, or M): (i)Most common unit of concentration • Gives number of moles of a substance in 1 liter of the given solvent. • Recall: 1 mole (mol) of a substance = 6.022 x 1023 units (atoms, molecules, ions, etc). • Molecular weight (MW): the mass of a substance that contains 1 mole. • Example: Find the concentration in Molarity (M) of 12.00g of benzene (C6H6) dissolved up to a total volume of 250.00 ml in hexane. MW benzene = 6 * (12.011) + 6 * (1.008) = 78.114 g/mol Conc. C6H6 = = 0.6144 M at. wt. H No. C’s No. H’s at. wt. C Make Sure Units Cancel!

27. Units and Concentrations • Units of Measurement • 2.)Expressions of Concentration: b.)Formality (F): (i)Concentrations expressed in M describe the actual concentration of a givenchemical species in solution. (ii) Some chemicals when placed in solution will dissociate or converted to multiple forms • Example: (iii) Not convenient to refer to the concentrations of each individual form. (iv) Instead, concentration of totalsubstanceoriginallyaddedtothesolution is used. • Formal concentration or Formality given in (mol/L) • Note: For compounds with a single form in solution, M = F Acetic Acid:

28. Units and Concentrations • Units of Measurement • 2.)Expressions of Concentration: b.)Percent Composition: (i)Weight Percent (wt/wt or w/w):Concentration expressed in terms of massofsubstance versus the total mass of the sample. (ii) Volume Percent (vol/vol or v/v):Concentration expressed in terms of volumeofsubstance versus the total volume of the sample. (iii) Weight-Volume Percent (wt/vol or w/v):Concentration expressed in terms of massofsubstance versus the total volume of the sample.

29. Units and Concentrations • Units of Measurement • 2.)Expressions of Concentration: b.)Percent Composition: (iv)Instead of expressing concentrations as a percentage, express in terms of: • parts per thousand (ppt) – x103 • parts per million (ppm) – x106 • Parts per billion (ppb) – x109 3.)Solution Preparation: a.)Dilution of a Solution: McVc = MdVd where: Mc = Molarity of substance in the concentrated solution Vc = volume of concentrated solution used Md = desired Molarity of the diluted solution Vd = total volume of final diluted solution

30. Units and Concentrations • Examples • How many grams of perchloric acid, HClO4, are contained in 37.6 g of • 70.5 wt% aqueous perchloric acid? How many grams of water are in • the same solution?

31. Units and Concentrations • Examples • What is the maximum volume of 0.25M sodium hypochlorite solution • (NaOCl, laundry bleach) that can be prepared by dilution of 1.00 L of • 0.80 M NaOCl?