Chemical Technician questions with complete solution1

Chemical Technician questions with complete
solutions



Sieving - answer-Method of passing the sample through a metal or plastic mesh of a
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uniform cross-sectional area to separate particles into uniform sizes.
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Freeze dryer - answer-It can remove a fairly large amount of water from a sample that
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contains thermally labile material.
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Acid digestion - answer-Sample preparation technique used prior to instrumental
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analysis of metals.
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Fusion technique - answer-In the decomposition and dissolution of solids during sample
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preparation, it is expensive and often the last resort.
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High signal-to-noise ratio - answer-Analytical methods or instruments' performance aim
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for
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Matrix - answer-It accounts for all the other components in the mixture that are not under
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investigation
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Primary standard - answer-When qualifying a working standard, what is the best type of
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reagent to use?
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Polyethylene - answer-What type of container should be used when handling or storing
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hydrogen fluoride?
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calcium gluconate - answer-Which of the following is a treatment for HF burns?
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Amber bottle - answer-Which of the following is the most appropriate container for
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hexane?
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Foam type - answer-If a fire extinguisher has a red body and a blue band, what is its
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content?
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Red - answer-According to NFPA, what color refers to flammability.
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Face velocity - answer-a value that determines the suitability of the chemical fume hood
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for its use (should be 80 to 100 feet per minute
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,Safety Date Sheet (SDS) - answer-A technical document, which is GHS compliant, that
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contains all the information related to the health hazard, storage, precautionary
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measures, emergency procedures, etc. when handling chemicals.
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Calibration curve - answer-A graphical representation of measuring signal as a function
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of quantity of analyte.
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Quality Manual - answer-It describes the policies and procedures the laboratory has to
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manage in relation to quality, or references where those procedures can be found. An
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essential requirement of ISO 9000 series of standards and ISO 17025.
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Capacity - answer-It is the nominal volume of water ( or mercury) contained, or delivered
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by an article of volumetric glassware, at its reference temperature.
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Pycnometer - answer-Used to determine the density of a liquid. v v v v v v v v v




Venting - answer-This is done during liquid-liquid extraction to release the pressure
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build-up inside the separatory funnel during shaking.
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Drying agent - answer-This is used to remove trace amounts of water in organic
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solutions. This can be added to the pooled organic layers before removal of the organic
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solvent
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Short stem funnel - answer-Used to filter hot mother liquor during recrystallization.
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Temperature - answer-In crystallization, crystal phases can be interconverted by
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varying...
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Inside the distilling flask and it should be just below the side arm of the flask - answer-
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Where should a thermometer be placed to determine the boiling point of the distillate?
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Steam distillation - answer-An organic compound decomposes at its boiling point. What
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is the most appropriate method for the recovery of the solid organic compound?
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Fractionating column - answer-It allows for many successive distillations to take place at
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once. It contains indentations or a packing material with lots of surface area.
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Equal to external pressure - answer-The boiling point of a liquid is the temperature at
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which the vapor pressure is
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Azeotrope - answer-A liquid mixture that has a constant boiling point and whose vapor
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has the same composition as the liquid.
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, Multiple extraction using three 50-mL portions of ether - answer-A 5-g organic solid is
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dissolved in 100 mL of distilled water. What is the best way to recover most of the
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organic solid?
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Place the reaction mixture in a dry ice-acetone mixture - answer-A reaction mixture
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needs to be cooled to -77C after refluxing. What is the best method to be used?
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Helium, Argon, Nitrogen - answer-Common carrier gases from gas chromatography
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ECD - answer-An air sample is subjected to gas chromatography for the analysis of
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Freon-11 (CCl3F). The detector that is most suitable for this analysis is
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Reversed-phase chromatography - answer-A non polar stationary phase and polar v v v v v v v v v


mobile phase
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Acetamide, acetone, dichloroethane - answer-Correct order of elution (first to last) from
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an HPLC column containing a reversed-phase packing
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The column has (+) resin where (-) species bind. - answer-In anion-exchange
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chromatography,
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Source, monochromator, sample, detector - answer-Correct order in which light passes
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through a UV-Vis spectrometer
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Tungsten - answer-Light source should be used in the wavelength range if 340-1000 nm
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To allow only light of a certain wavelength to pass from the source to the sample -
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answer-Purpose of monochromator
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The relationship between absorbance and concentration is not linear at high
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concentration - answer-Why must solutions with high concentrations be diluted prior to
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analysis via Beer's law?
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Flame - answer-Widely used continuous atomization method in AAS. It is also the most
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reproducible of all liquid-sample introduction methods that have been developed for
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AAS to date.
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The width of an atom's absorption band is narrow - answer-A hollow cathode tube lamp
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is necessary in AAS because
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m/z ratio - answer-A mass spectrum plots the intensity of each ion versus its
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MALDI - answer-A soft ionization method in mass spectrometry that is typically applied
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to biomolecules that involves a laser striking a solid matrix to ionize that analyte without
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fragmentation or decomposition
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