Chem. 31 8/28 Lecture What is Quantitative Analysis? (and Why is it important?) Quantitative Analysis is the determination of a compounds concentration (or mass or amount) in a sample Some examples of where a compounds concentration is important: level of intoxication from blood alcohol content determine whether a compound (e.g. F- in drinking water) is beneficial or harmful risk of having health problems (such as from high LDL concentrations or low HDL concentrations) Course Instructors Dr. Roy Dixon (lecture and sect. 2 of lab) I have been teaching this class for over 20
years My educational and research background is in analytical chemistry (with work on environmental and biological problems) Now, Im teaching less as Department Chair Dr. Jahansooz Toofan (lab sect. 4, 6, and 7), Dr. Alexander Gunn (lab sect. 2) Dr. Justin Miller Schulze (lab sect. 3) and Ms. Heidi Van Atta (lab sect. 5) Roll Call Sign in to sheet being passed around Handouts Syllabus Other materials will be posted online Typical Lecture Style Mix of whiteboard and Powerpoint slides
Use whiteboard for working out detailed problems Use Powerpoint slides for covering review material (e.g. Chapter 1) or material where having good graphics helps Powerpoint slides will be made available on website Announcements given in first few minutes Why is This Course Valuable? Analysis of chemicals is common in other chemistry classes (e.g. Chem. 25, Chem. 125, Chem. 141, Chem. 161, etc.). Many of the jobs both within chemical industry/pharmaceutical industry and in applied areas (e.g. environmental service and biotech) involve chemical analysis.
Examples of Chemical Analysis from Term Projects in Chemical Instrumentation (Chem 133 S16) Biodiesel Analysis (3 projects) Biodiesel is being produced on campus from waste cooking oil Composition can affect lifetime and use in cold weather In addition, analysis is needed for problematic compounds (methanol, glycerol, other glycerides, free Example fatty acid: CH3(CH2)7CH=CH(CH2)7CO2H R fatty acids) R O H C OH = Oleic = C18:1
3 O OH R" O O fatty acid methyl esters (FAMEs) C18:2 C18:1 140 C16
130 120 110 C17 C18 15.235 + H3C C18:3 150 O O
ADC1A, ADC1CHANNELA(DHFB\CALIBRATIONOILSPON2016-05-0517-32-10\050516000003.D) mV R' O R" triglyceride OH 11.450 H3C O +
+ O 8.663 9.211 R' O 6.420 - 6.764 O 4.834
H3C 0.868 O 1.309 O 2 4 6 8 10
12 14 min Traditional vs. Modern Methods Characteristic Traditional Modern Equipment Glassware and balances (low cost) Instruments (high cost)
Precision High Moderate Speed slow fast Sensitivity low high Selectivity
minimal Good to great Chapter 1 Measurements and Titrations No measurement is valuable unless it is given with units and some measure of uncertainty Units Chapter 1 Uncertainty Chapters 3 and 4 Units of Measure Most Basic SI base units (important ones) Measure Unit_____ Length meter (m)
Mass kilogram (kg) Time second (s) Temperature Kelvin (K) Amount Mole (mol) (only one with multiplier) Units of Measure Directly Derived from Base Units Volume: cube volume = l3 so units = m3 l Density = m/V so kg/m3 Pressure = force(kgm/s2)/area(m2) = kg/ (s2m) Units of Measure Other metric units (not directly in SI
units) Density (g/cm3) Pressure (Pascals or Pa = kg/(s2m)) Non-metric units (used commonly) For pressure 1 atmosphere (atm) = 101300 Pa English/Other system (not emphasized here) Units of Measure Metric Multipliers (ones you should know) Name Abbreviation Multiplier Kilo k x103 Centi c x10-2 Milli m
x10-3 Micro m x10-6 Nano n x10-9 Analytical chemists like small quantities. An instrument that can detect 1 fg (1 x 10-15 g) is better than an instrument that can detect 1 pg (1 x 10-12 g) Unit Conversion Example Problem Convert the density of lead from g/cm3 to kg m-3 if density = 11.7 g cm-3. Concentration Units General form massor molessolute massor molesor volumeof solution(or solvent)
Note: sometimes, volume is required in the denominator to be strictly considered concentration, but for this class mass ratios or mole ratios will be considered to be an expression of concentration
