Analytical Chemistry: UV-Vis Spectoscopy

What is the composition of Globar rod which is used as a source in Mid IR spectroscopy?

• Silicon dioxide
• Silicon carbide
• Silver carbide
• Silver chloride

Which of the following is TRUE for emission spectra?

• Excitation wavelength is scanned and the emission wavelength is scanned.
• Excitation wavelength is scanned and the emission wavelength is fixed.
• Excitation wavelength is fixed and the emission wavelength is fixed
• Excitation wavelength is fixed and the emission wavelengths are scanned.
• None of these answers is true

How is Tungsten Halogen lamp differ from normal Tungsten filament lamp used in absorption spectroscopy?

• Iodine is coated on tungsten filament
• It has a tungsten filament and is filled with inert gas
• Iodine is added to inert gas
• Iodine is added to normal filling gas

Which is NOT an appropriate detector for a spectrophotometer?

• charged coupled device
• thermal conductivity
• photomultiplier tube
• phototube
• photodiode array

In photometers, the readings of the specimen are initially obtained in the form of which of the following parameters?

• Transmittance
• Volume
• Wavelengths
• Absorption

If a sample of hexane with benzene had an absorbance of 0.153 at 256 nm in a cuvette with 1.000-cm path length, find the concentration of benzene in molarity

• 7.59×10^-4 M
• 1.51×10^-4 M
• 6.69×10^-4 M
• 5.41×10^-4 M

Beer’s law works for ___ radiation passing through a ___ solution in which the absorbing species is ___ in a concentrationdependent equilibrium

• polychromatic ; dilute ; participating
• polychromatic ; dilute ; not participating
• monochromatic; concentrated; not participating
• monochromatic; concentrated; participating
• monochromatic; dilute; not participating

Which of the following is TRUE for excitation spectra?

• Excitation wavelength is fixed and the emission wavelength is fixed.
• Excitation wavelength is fixed and the emission wavelengths are scanned.
• None of these answers is true.
• Excitation wavelength is scanned and the emission wavelength is scanned.
• Excitation wavelength is scanned and the emission wavelength is fixed.

In the diagram of single beam photometer given below, identify the component that is not marked.

• Interference filter
• Monochromator
• Absorption filter
• Sample holder

A solution prepared by dissolving 25.8 mg of benzene (78.11 g/mol) in hexane (86.16 g/mol) and diluting to 250 mL had an absorption peak at 256 nm and an absorbance of 0.266 in a 1.000-cm cell. What is the concentration of benzene solution?

• 1.32×10^-3 M
• 1.20×10^-3 M
• 1.20 M
• 1.32 M