analytical exam 3
in spectrophotometry, different molecules absorb light at different ______
wavelengths
which is the hottest region of the plasma torch in ICP
2 plasma region
which of the following is not one of the detectors used in a spectrophotomete? infra-red detector electron capture detector photomultiplier detector photodiode array
electron capture detector
in an ___, the dependent variable is the intensity of emission and the independent variable is the wavelength
emission spectrum
which of the following statement(s) about the fluorescense and fluorometer is (are) TRUE?
fluoresecne is an example of luminescence, fluorescence is more sensitive than absorbance spectrophotometry, the two monochromators are placed 90 from one another in a flourometer instrument.
. Two monochromators positioned at right angles is a characteristic of which instrument?
fluormeter
spectrophotometers use a monochromator containing a _____ to select the ____ assigned for measuring the absorbance of an analyte.
grating, wavelength respectively
which of the following statements is correct
X-ray radiation has a shorter wavelength than visible light
in an emission spectrum the ___ is constant and the ___ is the variable
^ex, ^em respectively
what is a chromophore
a group of atoms in a compound responsible for the absorption of electromagnetic radiation
Which of the following is proportional to concentration
absorbance
a solution has an absorbance of .62 at 595 nm. As you make the solution more and more dilute, what happens to its absorbance at 595 nm
absorbance will decrease
the general types of atoic spectroscopy are :
absorption, fluorescenece and emission
In a scanning absorption spectrum, the dependent variable is .......... and the independent variable is .............
absorption, wavelength
in a scanning absorption spectrum, the dependent variable is ______and the independent variable is _____
absorption, wavelength
the fuel gas used in flame atomic-absorption spectroscopy is ___ and the oxidant is ___
acetylene, air respectively
in strong acids, the measured pH is higher than the actual pH because the glass is saturated with H+ and cant be further protonated. This error in pH measurements is known as
acid error
the gas used in Inductively coupled plasma is ___
argon
the purpose of a blank is to
cancel and subtract readings due to the absorbance of the reagents added to the analyte
When analyzing an analyte using atomic absorption spectroscopy the releasing agent is added to minimize the ________ interference
chemical
Atomic emission originates from excited energy levels. Atoms in inductively-coupled plasma are promoted to these higher levels by:
collisions with other atoms and ions in the plasma
at low concentrations the fluorescence intensity will generally be proportional to the ___ of the analyte
concentration
A ____ lamp is used as a source of light in uv-spectropohotmer, whereas a ____ lamp is used in case of atomic absorption spectroscopy.
deuterium arc, hollow cathode respectively
monochromatic light is defined as
electromagnetic radiation of one wavelength
one of the main advantages of a furance atomic absorption is that:
it requires only a very small quantity of a sample
what does the term monochromator mean
light of only one wavelength
When the H+ is very low and NA+ is high the electrode starts to respond to Na+ gving a pH ____ than the true pH. This is known as _____
lower, sodium error
for which of the following types of electromagnetic radiation would the photon have the lowest energy
microwave
the intensity of the transmitted light is detected with a ____which is one of the light detectors
photodiode
the most common spectrophotometers are used in the ___ and ____ regions of the spectrum, and some of these instruments also operate into the near-infrared region as well.
ultraviolet, visible respectively
For a given element, the atomization method that can detect the lowest concentration is
plasma
When analyzing an analyte using atomic absorption spectroscopy the ________ is added to minimize the chemical interference
releasing agent
spectrophotometric analysis based on Beer's Law
requires the use of monochromatic light
compared to atomic-absorption (AAS) spectroscopy, inductively coupled plasma (ICP) has the advantage of providing:
simultaneous multi-element analysis
Interference resulting when two or more elements have emission spectra in overlapping wavelengths is referred to as:
spectal interference
the basis of the technique of chromatograpghy for seperating components of a mixture is
the interaction of the components with both stationary and mobile phases
which of the following is not one of the detectors used in a spectrophotometer?infrared detector, photomultiplier detector, thermal conductivity detector, photoiode array
thermal conducivity detector
____ is the lamp used in visible spectrophotometry
tungsten
which of the following statements about fluormetry are true
two monochromators are use in a fluormeter instrument