ANALYTICAL CHEMISTRY Chem 333

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ANALYTICAL CHEMISTRYChem 333
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Chapter 2Tools of the Trade
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Analytical Balances
Overhead
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Weighing Errors
Temperature warm air trapped inside bottles
decreases mass 10-15 mg
Fingerprints a few tenths of a mg per print
Atmosphere hygroscopic samples absorb water
Buoyancy an object displaces a certain volume
of air. Important when density of object is
different than that of the weights.
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Buoyancy Correction
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Quartz Crystal Microbalance
Overhead
Box 2-2 in text
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Cantilevers As Balances
Used in Atomic Force Microscopy (AFM)
Etched Si AFM Probe
Tip
Cantilever
100 mm
Tapping Mode
http//www.di.com
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Basic Techniques
Overhead
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Volumetrics
TC To Contain Flasks
TD To Deliver Pipets
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Caring for Volumetrics
1. Clean with strong oxidizer (e.g., acid)
2. Do not soak in Strong Base!!!
3. Surface should be hydrophilic (i.e., wet the
surface)
4. Never heat calibrated glassware
Dirty Glassware
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Density of H2O
For work that requires ultimate accuracy, the
thermal expansion of H2O must be taken into
account.
Overhead
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Laboratory H2O
Tap Water initial cleaning only
De-ionized may contain organics bacteria
non-electrolytes particulates
Filtered removes organics and/or particulates
Reagent Grade highest purity available
Other Grades PRA Pesticide Residue
Analysis HPLC High-Performance Liquid
Chromatography ACS American Chemical Society