ELEMENTARY QUANTITATIVE ANALYSIS

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WELCOME! ELEMENTARY QUANTITATIVE ANALYSIS CHEM
221
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ELEMENTARY QUANTITATIVE ANALYSIS CHEM 221, Fall
2007 Tues Thur 930-1045, Rm. 112 Hamilton
Hall COURSE OUTLINE Instructor Dr. Robert
Powers
Office Labs Address 722 HaH 720-721
HaH Phone [phone] e-mailrpowers3_at_
unl.edu web page http//bionmr-c1.unl.edu/ Offi
ce Hours 1030-1130 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 [phone] office 721 HaH Ms.
Kelly Mercier phone [phone] office 721
HaH Mr. Rob Waters contact Resource center
e-mail bor9455_at_hotmail.com
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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.
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Lecture Topics Date Chapter Topic Problems Au
g 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,1,2,4,7,9,16,23,29,3
1,33,38 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,6,7,8,10,13,17,23,2
4 Nov 29 Chap 16 Redox Titrations 16-A,C,1,2,7,1
4,15,16,24 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
1000-1200
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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)
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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

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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

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Lab Notebook Techniques
This Notebook Page is incomplete and a Useless
Document. Limited Detail.
This Notebook Page Has Precise Description with
Adequate Detail
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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.
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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.
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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.
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Microsoft Excel Demo
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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
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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?
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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) dont use the entire sample
• (ii) consistency in sample collection

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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

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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) 302442-445
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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,
S57S62 (2000)
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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

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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

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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.
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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

International Prototype Meter standard bar made
of platinum-iridium
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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
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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
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Units and Concentrations

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

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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. Cs
No. Hs
at. wt. C
Make Sure Units Cancel!
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Units and Concentrations

• Units of Measurement
• 2.) Expressions of Concentration
• b.) Formality (F)
• (i) Concentrations expressed in M describe the
  actual concentration of a given chemical 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 total substance
  originally added to the solution is used.
• Formal concentration or Formality given in
  (mol/L)
• Note For compounds with a single form in
  solution, M F

Acetic Acid
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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 mass of
  substance versus the total mass of the sample.
• (ii) Volume Percent (vol/vol or v/v)
  Concentration expressed in terms of volume of
  substance versus the total volume of the sample.
• (iii) Weight-Volume Percent (wt/vol or w/v)
  Concentration expressed in terms of mass of
  substance versus the total volume of the sample.

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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

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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?
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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?