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Analytical Chemistry

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  • What are the two principal means of dissolving inorganic materials?
    By adding: (1) hydrochloric acid (2) nitric acid as a strong oxidizing acid
  • What do you call this tool and what do you use it for?
    MEASURING PIPET - used for accurate measurements, especially for small volumes, if they are calibrated at the particular volume wanted
  • What's the purpose of wash bottles in the laboratory?
    to be used for quantitative transfer of precipitates and solutions and to wash precipitates
  • What's the usual temperature of a drying oven in the laboratory?
    The usual drying temperature is about 110◦ C, but many laboratory ovens can be heated up to temperatures of 200 to 300◦ C
  • What is an aliquot?
    it is an analysis sample.
  • How do microwaves heat?
    Microwaves heat by causing molecules to rotate and ions to migrate.
  • What is the difference between dry ashing and wet digestion?
    dry ashing-heating at a high temperature in a muffle furnace, while wet digestion involves heating in the presence of a strong acid and an oxidizing agent
  • In a digestion process, is it advisable to add perchloric acid directly to organic or biological material? Why?
    No. This is simply to prevent evaporation of the perchloric acid to near dryness, or a violent explosion may occur
  • What do you call this tool and what do you use it for?
    BURETS - used for the accurate delivery of a variable amount of solution. Its principal use is in titrations
  • What do you call this tool and what is it for?
    DESSICATORS - to keep samples dry while they are cooling and before they are weighed and, in some cases, to dry a wet sample
  • Why glass filters are not recommended for concentrated alkali solution?
    because of high concentration the alkali will attack the glass filter and will destroy it
  • How do you define GROSS SAMPLE?
    a sample that is representative of the whole
  • In a folded filter paper for filtration, why do is there a need to tear about 1cm from the corner to the inside edge?
    Because it will allow a good seal against the funnel to prevent air bubbles from being drawn in
  • What is PFF?
    Protein – Free Filtrate
  • What is grab sample?
    It is one sample taken at random and assumed to be representative
  • What is the purpose of syringe pipets?
    Syringe pipets are useful for delivering microliter volumes.
  • How do you calibrate a pipet?
  • What type of hood is often outfitted with high intensity UV lamps?
    Biohazard hood
  • What do you call this tool and what do you use it for?
    FUME HOODS - used when chemicals or solutions are to be evaporated
  • Why is it important to maintain cleanliness in the laboratory specially the cleanliness of glasswares?
    If films of dirt or grease are present, liquids will not drain uniformly and will leave water breaks or droplets on the walls, the calibrations will be in error
  • What is the purpose of muffle furnace in the laboratory?
    it is used to ignite samples to high temperatures, either to convert precipitates to a weighable form or to burn organic materials prior to inorganic analysis
  • What do you call that process of converting nitrogen to ammonium sulfate?
    Kjeldahl digestion or analysis
  • What do you call this tool and what do you use it for?
    Electronic analytical balance- precision measuring instrument to determine the mass of solid objects, liquids, powders and granular substances
  • What do you call this tool and what do you use it for?
    VOLUMETRIC FLASK - used for the dilution of solutions to a certain volume
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