Chem 210 Exam 4 Study Questions with Correct Answers Already Graded A+

Chem 210 Exam 4 Study Questions with Correct Answers Already Graded A+ 1. advantages of a furnace over a flame in atomic absorption - ANSWER -a smaller sample amount is needed -higher sensitivity b/c the atmoized sample is in the optical path length 2. Anode in hollow cathode lamp - ANSWER Positively charged electrode made of tungsten 3. Ne or Ar gass in hollow cathode lamp - ANSWER It is atomized when a potential of 500 V is applied between the electrodes 4. Hollow cathode lamp 1 - ANSWER It is a cylindrical and made of the desired element while emission lines are desired 5. Transparent window in hollow cathode lamp - ANSWER it is made of glasss or quartz and allows radiation to passs through uninterupted 6. Flame AA - ANSWER it is used to atomize the sample 7. Hollow cathode lamp aa - ANSWER it is composed of the same element that is being analyzed in the sample 8. DETECTOR AA - ANSWER it is typically a photomultiplier tube that generates an electrical signal when struck by photons 9. monochromator - ANSWER It is used to select one line of radiation from the source and remove as much emission for the atomizer as possible. 10.Atomic absorption schematic - ANSWER 11.Atomic analysis sensitivity - ANSWER least sensitivity flame atomic absorption furnace atomic absorption plasma emission inductively coupled plasma-mass spectrometry highest sensitivity 12.Combustion flame - ANSWER -Most common fuel oxidant combination is acetylene-air -requires at least 10 ml of sample 13.Graphite Furnace AAS - ANSWER -Must be programmed to dry char, then atomize sample -maximum recommended temp is 2550 C -requires tens of microliters of sample tively coupled plasma - ANSWER -Temperature reach up to 10,000 K -Very expensive -can be coupled with mass spectrometry 15.x electrode in a voltaic cell - ANSWER -anode -loses mass -electrons in the wire flow away from -anions from the salt bridge flow towards 16.Y electrode in voltaic cell - ANSWER Electrons in the wire flow towards cathode gains mass cations from the salt bridge flow towards 17.IN an alkaline solution with a high Na + con, a glass ph electrode tends to indicate a PH that is ?? - ANSWER Lower than actual PH bc The Na+ ions bind to the same exchange sites as the H+ ions on the surface of the glass electrode. The electrode responds to Na+ as if H+ is present, leading to an apparent pH that is lower than the actual PH 18.Possible errors of measuring PH with a glass combination electrode - ANSWER -uncertainty in the PH of buffer solutions -junction potential -Acid error at low Ph 19.Glass electrode - ANSWER Consist of a thin doped glass membrane that is sensitive to a specific ion, typically single charged ions such as H or Na . und electrodes - ANSWER Consist of a conventional electrode surrounded by a membrane that is selectively permeable to the analyte of interest or it generates a species that the inner electrode is sensitive to, in response to the analyte. cal interference - ANSWER interference from any component of the sample that reduces atomization of the analyte ral interference - ANSWER interference from the overlap of analyte signal with signals from other atoms or molecules, the flame, or the furnace ric interference - ANSWER interference by ions with a similar massto-charge ratio ation interference - ANSWER interference of analyte atoms which decreases the concentration of neutral atoms 25.Hollow cathode lamp - ANSWER A source that emits narrow atomic lines 26.Zeeman effect - ANSWER The splitting of atomic lines in the presence of a parallel magnetic field sing agent - ANSWER An additive that reduces chemical interference zation - ANSWER The conversion of sample components into individual atoms ral interference 1 - ANSWER Signal from species not under study that overlaps with the analyte signal 30.Nebulization - ANSWER The conversion of a liquid sample into very small droplets x modifier - ANSWER An additive that prevents the loss of analyte during charring 32.Boltzman distribution - ANSWER Describes the population ratio of different states at thermal equilibrium 33.Pressure Broadening - ANSWER An increase in the atomic linewidth due to collisions between atoms c emission - ANSWER Atoms are thermally promoted to the excited state through collisions in the plasma. As they return to a lower energy state, they emit photons. No excitation source outside of the plasma is required. 35.Atomic Florescence - ANSWER The sample is atomized in the flame. A laser is used to promote the atoms in the flame to an excited state. As the atoms return to the ground state they fluoresce.