Instrumental Analysis - Exam 2 questions with verified
answers
A Term Ans✓✓✓ Zone broadening due to part of multitude of
pathways a molecule can find its way through a column.
Independent of solvent velocity.
Band broadening occurs due to different path lengths
Acidic Error Ans✓✓✓ In strong acidic solution, [H+] is very large, and
[Metal-] is very small. Glass electrodes respond to them as Gl-.
pH values are LARGER
Activation Polarization Ans✓✓✓ Kinetic.
Magnitude current is limited by rate of one or both of the electrode
reactions.
Rate of electron transfer between the reactants and the electrodes
Pronounced in reactions that yield gases because gas evolution is
involved and slow.
Overpotential to overcome activation energy.
Decreases with increasing temperature.
,Activity coefficients Ans✓✓✓ Accounts for effects of electrolytes on
chemical equilibria.
Depends on ionic strength
Advantages of Ultrasonic nebulizer Ans✓✓✓ Plasma energy is not
wasted, so more energy for atomization.
Concentration needed for adequate signal is reduced a lot.
Lower detection limit
Ag/AgCl Reference Electrode Ans✓✓✓ Half cell reaction: AgCl(s) + e- <-
> Ag(s) + Cl-
Agarose Ans✓✓✓ DNA and RNA separaition.
Alkaline Error Ans✓✓✓ In strong basic solution, [H+] is extremely small
and [Metal+] is very large. Glass electrodes respond to the
concentration of both hydrogen and alkali metal ions such as Na+.
pH values are LOWER
Amperometric Ans✓✓✓ Sensors
,Amperometry Ans✓✓✓ measures electric current at constant applied
potential and relating measured current to concentration
Analyte Interferences Ans✓✓✓ Change the magnitude of the analyte
signal itself.
Physical and Chemical Interferences
Anode (Copper) Ans✓✓✓ copper oxidized to copper ion, giving up its
electrons to the electrode. Copper ions move away from electrode to
bulk of solution, while anions, such as sulfate and hydrogen sulfate
ions, migrate toward copper anode
Anodic stripping method Ans✓✓✓ working electrode behaves as
cathode during deposition step and as anode during stripping, analyte
is oxidized to original form
Argon Plasma Ans✓✓✓ Argon ions and electrons are principal
conducting species. Can absorb enough power from external source to
maintain temperature at which further ionization sustains plasma.
As Temperature increases what happens to viscosity and conducitivity?
Ans✓✓✓ viscosity decreases and conductivity increases
, As you get closer the the cathode, [Cd2+] does what? Ans✓✓✓
decreases due to increasing reduction potential and increasing [Cd}
Atomic Emission Spectroscopy Schematic Ans✓✓✓ Atomizer;
Wavelength Selector; Detector; Amplifier; Computer
Atomization Ans✓✓✓ Elements in sample are converted to gaseous
atoms or elementary ions
B Term Ans✓✓✓ Longitudinal Diffusion.
At low velocities, this term increases. Therefore higher velocities
needed to reduce this and reduce plate height to improve column
efficiency
Benefits to potentiometry Ans✓✓✓ Relatively free from interferences
and provide rapid, and convenient
Nondestructive means of quantifying many ions and cations
Simple and inexpensive
Biocatalytic Membrane selective electrodes Ans✓✓✓ Biosensors.
Enzymes.
answers
A Term Ans✓✓✓ Zone broadening due to part of multitude of
pathways a molecule can find its way through a column.
Independent of solvent velocity.
Band broadening occurs due to different path lengths
Acidic Error Ans✓✓✓ In strong acidic solution, [H+] is very large, and
[Metal-] is very small. Glass electrodes respond to them as Gl-.
pH values are LARGER
Activation Polarization Ans✓✓✓ Kinetic.
Magnitude current is limited by rate of one or both of the electrode
reactions.
Rate of electron transfer between the reactants and the electrodes
Pronounced in reactions that yield gases because gas evolution is
involved and slow.
Overpotential to overcome activation energy.
Decreases with increasing temperature.
,Activity coefficients Ans✓✓✓ Accounts for effects of electrolytes on
chemical equilibria.
Depends on ionic strength
Advantages of Ultrasonic nebulizer Ans✓✓✓ Plasma energy is not
wasted, so more energy for atomization.
Concentration needed for adequate signal is reduced a lot.
Lower detection limit
Ag/AgCl Reference Electrode Ans✓✓✓ Half cell reaction: AgCl(s) + e- <-
> Ag(s) + Cl-
Agarose Ans✓✓✓ DNA and RNA separaition.
Alkaline Error Ans✓✓✓ In strong basic solution, [H+] is extremely small
and [Metal+] is very large. Glass electrodes respond to the
concentration of both hydrogen and alkali metal ions such as Na+.
pH values are LOWER
Amperometric Ans✓✓✓ Sensors
,Amperometry Ans✓✓✓ measures electric current at constant applied
potential and relating measured current to concentration
Analyte Interferences Ans✓✓✓ Change the magnitude of the analyte
signal itself.
Physical and Chemical Interferences
Anode (Copper) Ans✓✓✓ copper oxidized to copper ion, giving up its
electrons to the electrode. Copper ions move away from electrode to
bulk of solution, while anions, such as sulfate and hydrogen sulfate
ions, migrate toward copper anode
Anodic stripping method Ans✓✓✓ working electrode behaves as
cathode during deposition step and as anode during stripping, analyte
is oxidized to original form
Argon Plasma Ans✓✓✓ Argon ions and electrons are principal
conducting species. Can absorb enough power from external source to
maintain temperature at which further ionization sustains plasma.
As Temperature increases what happens to viscosity and conducitivity?
Ans✓✓✓ viscosity decreases and conductivity increases
, As you get closer the the cathode, [Cd2+] does what? Ans✓✓✓
decreases due to increasing reduction potential and increasing [Cd}
Atomic Emission Spectroscopy Schematic Ans✓✓✓ Atomizer;
Wavelength Selector; Detector; Amplifier; Computer
Atomization Ans✓✓✓ Elements in sample are converted to gaseous
atoms or elementary ions
B Term Ans✓✓✓ Longitudinal Diffusion.
At low velocities, this term increases. Therefore higher velocities
needed to reduce this and reduce plate height to improve column
efficiency
Benefits to potentiometry Ans✓✓✓ Relatively free from interferences
and provide rapid, and convenient
Nondestructive means of quantifying many ions and cations
Simple and inexpensive
Biocatalytic Membrane selective electrodes Ans✓✓✓ Biosensors.
Enzymes.
