Chemical Instrumentation CHEM*3440 Mid-Term Examination Fall 2006 Tuesday, October 24
Duration: 2 hours. You may use a calculator. No additional aids will be necessary as a series of data and equation sheets are included as part of the examination.
Chemical Instrumentation CHEM*3440
Mid-Term Examination Fall 2005 TUESDAY, OCTOBER 25, 2005 Duration: 2 hours. You may use a calculator. No additional aids will be necessary as a series of data and equation sheets are included as part of the examination p
CHEM*3440 Instrumental Analysis Mid-Term Examination Fall 2004 Duration: 2 hours 1. (10 points) An atomic absorption experiment found the following results for a [Pd] ppm series of standard solutions for dissolved palladium metal ion. The data were plotte
CHEM*3440 Instrumental Methods Mid-Term Examination October 28, 2003 Duration: Two Hours 1. (5 points) A real battery actually behaves more like a voltage source in series with a resistance, called its internal resistance. (This arises from the fact that
CHEM 3440 Final Examination Fall 2005 Duration: 2 hours 1. (10 points) Chondrotinase is a protein which was analyzed by ESI FT ICR MS by Kelleher et al. in 1997. Some spectra are shown below. Mass here is reported in daltons (Da) = atomic mass unit (amu).
1 CHEM*3440 FINAL EXAMINATION Fall 2004 Duration: 2 hours 1. (8 points) A certain molecule was analyzed by electrospray ionization mass spectrometry. There are a lot of overlapping bands, but a tetramer of the molecule appears with a residual charge of +7
Atomic nuclei consist of protons and neutrons held together by the strong nuclear force, in balance with the electromagnetic and weak forces. Most nuclei are unstable and decay by various emission pathways.
We will examine three thermal analytical techniques: Thermogravimetric Analysis (TGA)
Differential Thermal Analysis (DTA) Differential Scanning Calorimetry (DSC)
TGA and DTA have found important
very short wavelength radiation 0.1 to 10 nm (100 ) Visible - Ultraviolet (UV) - Vacuum UV (VUV) - Extreme UV (XUV) - Soft X-ray - Hard X-ray - Gamma Ray often report photon energies, rather than wavelength. (above range is from 125 keV dow
In general there are four steps associated with a mass spectroscopic experiment: ! generate gas-phase molecules from analyte (solid, liquid, solution, etc.)
" ionize those molecules # separate
Another spectroscopic technique which probes the rovibrational structure of molecules.
C.V. Raman discovered in 1928; received Nobel Prize in 1931. Can probe gases, liquids, and solids. Must u
Infrared is Rovibrational Spectroscopy
Wavelengths between 0.8 m to 1 mm. Associated with changes in nuclear motion (vibrations and rotations).
In gas phase, rotational transitions are resolved; in liquid phase,
Types of Luminescence
Fluorescence Happens quickly after the absorption of the initial photon (s to ps lifetime).
Phosphorescence Happens slowly after the absorption of the initial photon (min to ms lifetime).
UV-Visible Electronic Transitions
This technique is mainly a study of molecules and their electronic transitions. Molar absorptivity (") ranges from 0 to 105.
Transitions with " < 103 are considered to be of low
Spectrum of Electromagnetic Radiation
Electromagnetic radiation is light. Different energy light interacts with different motions in molecules.
Radiofrequency Microwave Infrare d UV-Visible Far UV - X-ray Gamma R
Digital Data Domain
An analog signal is continuously varying in time. A digital signal consists of discrete samples of an analog signal. It is discretized in both coordinates (time and signal amplitude).
Sample Spectrum 10 9 8 7 6 5
Circuit Diagram of 741 Op Amp
Thanks to Tony van Roon in the Electronics Shop for the use of this picture.
Schematic of Op Amp
While op amp is complex in detail, there are really only three
In All experiments there is: Sample Response: the instrument's response when the analyte is present.
Blank Response: the instrument!s response when the analyte is absent. The Signal is the difference between the sample and
CONVENTION: Electrical current ows from a region of positive potential energy to a region of more negative (or less positive) potential energy.
Truth is that electron ow is electrical current.
Statistics and Analytical Chemistry
Random noise is part of any analytical measurement. Precise and Accurate answers demand a statistical analysis of the data. 1. How much analyte is present? 2. Is one test protocol better than another? 3. Are the results
The Analysis Concept
What is it? How much is there? How does it behave?
Sample for Analysis
Concept of the Instrument
Electrons, photons, atoms, molecules, ions, heat, .
Heat, ions, molecules, atom