CHE 315: UV-Visible Spectrophotometry and Colorimetry

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What type of lamps are used in UV-Visible spectrophotometry?

Deuterium and tungsten filament (correct)

Mercury and xenon

Fluorescent and incandescent

Halogen and LED

In which wavelength range does colorimetry mainly work?

200-800 nm

400-700 nm (correct)

100-500 nm

700-1000 nm

What is the purpose of a monochromator in a UV-Visible spectrophotometer?

To analyze solid samples

To emit visible light

To separate polychromatic light into monochromatic light (correct)

To generate UV light

Why are colorimeters considered cheap and easy to operate?

Due to the use of simple narrow band filters (C) Signup and view all the answers

Which region of the electromagnetic spectrum do UV-visible spectrophotometry and colorimetry cover?

UV to visible region (B) Signup and view all the answers

Why are UV-Visible spectrometers more expensive compared to colorimeters?

They are equipped with two different lamps (A) Signup and view all the answers

What is the wavelength of maximum absorption known as?

Lambda max (λmax) (B) Signup and view all the answers

In the UV-visible spectrum of lycopene, what is the lambda max value?

471 nm (D) Signup and view all the answers

What does the detector in a UV/VIS spectrophotometer or colorimeter measure?

Intensity of transmitted light (D) Signup and view all the answers

What is the ratio between the intensities I / I0 defined as?

Transmittance T (B) Signup and view all the answers

Which law is applied for quantification based on the absorptivity of pure compounds?

Beer-Lambert Law (B) Signup and view all the answers

What term refers to the attenuation of transmitted light by sample molecules in solution?

''Transmittance T'' (A) Signup and view all the answers

What can happen if the molecules in a solution are at high concentrations?

They aggregate, leading to incorrect readings (B) Signup and view all the answers

Why is it essential for the solution not to contain molecules that emit fluorescence when excited?

To avoid erroneous readings (D) Signup and view all the answers

What is necessary for determining the concentration of an unknown sample using UV/VIS spectroscopy?

Creating a calibration curve (D) Signup and view all the answers

How is a calibration line obtained for UV/VIS spectroscopy analysis?

Linear regression of absorbance values (C) Signup and view all the answers

What does the Lambert-Beer Law form the basis for in UV/VIS spectroscopy?

Determining unknown sample concentrations (D) Signup and view all the answers

What purpose do UV/VIS spectra serve in identifying components in a sample solution?

Identifying sample components (C) Signup and view all the answers

What allows specific compounds to be identified in UV/VIS spectroscopy?

Position and profile of the absorption peaks (C) Signup and view all the answers

How is the blank in UV/VIS spectroscopy typically measured?

Intensity of light transmitted through the solvent (A) Signup and view all the answers

What is the purpose of measuring the absorbance value of a peak in UV/VIS spectroscopy?

To calculate the sample concentration (D) Signup and view all the answers

Why is a blank measurement necessary in UV/VIS spectroscopy?

To measure the intensity of transmitted light through the solvent (C) Signup and view all the answers

In which market segments is UV/VIS spectroscopy commonly used as a quantitative analytical technique?

Water Testing, Food and Beverages, Pharmaceutical, Chemical and Biotech Industry (B) Signup and view all the answers

What is added to a cuvette for blank measurement in UV/VIS spectroscopy?

Solvent like water or alcohol (B) Signup and view all the answers

How is absorbance calculated in a spectrophotometer?

By dividing the transmitted intensity of the sample solution by the corresponding values of the blank (A) Signup and view all the answers

What is the purpose of using absorbance values for standard solutions in spectrophotometry?

To plot the calibration curve (B) Signup and view all the answers

Why is it important to measure absorbance in a spectrophotometer?

To quantify the amount of light absorbed by sample molecules (B) Signup and view all the answers

What role do standard solutions play in UV/VIS spectrophotometric analysis?

They aid in plotting calibration curves (B) Signup and view all the answers

Why is it necessary to extrapolate concentrations from a calibration curve in spectrophotometry?

To quantify unknown sample concentrations (A) Signup and view all the answers