Quiz 13 Flashcards
- What is the use of High-performance liquid chromatography (HPLC)?
to identify component of mixtures
to separate component of mixtures
to purify the analyte of interest
all of the above
all of the above
High-performance liquid chromatography (HPLC) is a technique in analytical chemistry used to separate the components in a mixture, and to identify and quantify each component. It was initially discovered as an analytical technique in the early twentieth century and was first used to separate colored compounds.
- In chromatography, what is a base line?
detectors response to the mobile phase
detectors response to the stationary phase
detectors response to the chromatogram
all of the above
detectors response to the mobile phase
baseline (in chromatography). The portion of the chromatogram recording the detector response when only the mobile phase emerges from the column.
- In chromatography, what is not a source of Base line noise?
sample
system problems
temperature variations in lab
volume of sample injected
volume of sample injected
- Both classical and instrumental methods can be used to determine the concentration of a specific elements or species in a compound. Which of the following pairs is the wrong combination of the type of analysis with its characteristic?
Gravimetric analysis - mass
Spectrophotometric analysis - density
Volumetric analysis - volume
potentiometric analysis – voltage
Spectrophotometric analysis - density
- In complexometric titration, the most common used chelating agent is EDTA (ethylenediamine tetraacetic acid). EDTA’s molecules will combine with metals to form chelate. EDTA is classified as a ?
bidentate ligand
hexadentate ligand
tetradentate ligand
monodentate ligand
hexadentate ligand
Ethylenediamine tetraacetic acid (EDTA) is a polyprotic acid containing four carboxylic acid groups and two amine groups with lone-pair electrons that chelate calcium and several other metal ions.An example of a Hexadentate ligand is Ethylene Diamine Tetra Acetic Acid (EDTA). It can bind through two Nitrogen and four Oxygen atom to a central metal ion. There is a total of six-pronged ligands including Nitrogen and Oxygen so it is known as Hexadentate.
- Which of the following statements about Mohr’s method is INCORRECT?
The pH of the reaction mixture should not be too high to prevent the formation of undesirable precipitates.
The pH of the reaction mixture should not be too low to prevent the conversion of chromate ions to dichromate ions.
This method is used to determine the concentration of chloride ions in a water sample.
A bluish-green precipitate can be observed at the end point of the titration.
A bluish-green precipitate can be observed at the end point of the titration.
- UV spectrophotometer and Visible Spectrophotometer sample cells, respectively.
Quartz (crystalline silica) and Glass
Glass and Quartz (crystalline silica)
test tubes and cuvettes
all of the above
Quartz (crystalline silica) and Glass
- Which of the following is not true about galvanic method of oxygen analysis?
Electrodes are composed of noble and base metals
It can measure dissolved content of oxygen
Its principle is based on electrolysis
It utilizes an electronic cell
Its principle is based on electrolysis
- To produce the proper monochromatic light necessary for the Atomic Absorption Spectroscopy (AAS), ______ are used.
hollow cathode lamps
cuvettes
electric rods
probes
hollow cathode lamps
AAS is an analytical technique used to determine the concentration of metal atoms/ions in a sample. Metals make up around 75% of the earth’s chemical elements. In some cases, metal content in a material is desirable, but metals can also be contaminants (poisons).
- In atomic absorption spectroscopy (AAS), if sample concentration is too high to permit accurate analysis in linearity response range; what should an analyst do?
sample dilution
using an alternative wavelength having a lower absorptivity
reducing the path length by rotating the burner hand
all of the above
all of the above
- A measure of the gravitational force of attraction exerted on a body is the
density
mass
weight
specific gravity
weight
- Cathode rays are composed of
positrons
electrons
protons
neutrons
electrons
- The kind of bond formed between atoms of the same electronegativity will be
covalent
polar covalent
non-polar covalent
ionic
non-polar covalent
- The formula for aluminum hydroxide is
AlOH
Al(OH)3
Al2(OH)3
Al3OH
Al(OH)3
- When calcium react with sulfur the compound formed is
Ca2S2
CaS2
CaS
Ca3S2
CaS
