UV visible spectroscopy

In summary, UV-Vis spectroscopy uses a radiation source to pass through a sample and a monochromator to produce a red light to pass through a blue solution of CuSO4. Double beam scanning spectrophotometers use a motor to split the incident beam and direct it to the sample and a blank for more accurate measurement. The position of the optical components depends on the model of the instrument. In terms of equilibrium, for the given reaction of N2O4 dissociating into 2NO2, with an initial amount of 0.1 mole of N2O4 and 0.06 mole remaining at equilibrium, the equilibrium constant can be calculated using the formula Keq = [NO2]^2/[N
  • #1
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Howdy,
i was wondering is anyone knows how a UV-visible spectroscopy works and how it differs to a double beam scanning spectrophotometer?
i know that UV visible spectroscopy needs a radiation source that is passed into a silt and then in a monochromator but how do u know how to poistion the monochromator to produce a red light to let's say to pass through a blue solution of CuSO4. And double beam scanning spectrophotometer uses motor what do those serve for?

and i have another question about equilibrium. if a 0.1 mole of N2O4 is introduced into 1L flask. the N2O4 dissociates into NO2 at equilibrium. 0.06 mole of N2O4 remain. Calculate the equilibrium constant for the reaction.
N2O4----->2NO2

Any help for any of the two questions would be awesome
Thanx :)
 
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  • #2
UV-Vis spectroscopy is a technique for analyzing samples through the excitation and emission spectra of known constituents. A double beam Scanning Spectrophotometer is an (expensive piece of) instrument that is used for such a measurement. It is more reliable than a (cheaper) single beam spectrophotometer, as it splits the incident beam, directing one part to the sample being analyzed and the other to a blank (reference sample). This way, variations in the sample composition as well as drift in the lamp output is eliminated.

As far as I'm aware, the optical components (including the monochromator) are positioned so as to make the beam pass through the sample/s (when placed in the sample holder/s). Adjustments to settings will depend on the exact model of the instrument being used.
 
  • #3


UV-visible spectroscopy is a type of spectroscopy that measures the absorption of UV and visible light by a sample. The basic principle is that the sample is irradiated with a broad range of UV and visible light, and the amount of light absorbed is measured. This absorption is then used to determine the concentration of the sample or to identify the molecules present.

A double beam scanning spectrophotometer is a type of UV-visible spectrophotometer that uses two beams of light, one passing through the sample and one through a reference solution. This allows for more accurate measurements and compensation for any changes in the light source.

To position the monochromator for a specific wavelength, the instrument needs to be calibrated using a known standard solution. This allows the operator to adjust the monochromator to the desired wavelength for the sample being measured.

In terms of equilibrium, the equilibrium constant (K) is a measure of the ratio of products to reactants at equilibrium. In this case, the equilibrium constant can be calculated using the expression K = [NO2]^2/[N2O4]. Using the given information, we can plug in the values to get K = (0.06)^2/(0.1-0.06) = 0.09. This means that at equilibrium, there are 0.09 moles of NO2 for every 1 mole of N2O4.
 

1. What is UV visible spectroscopy?

UV visible spectroscopy is a technique used to analyze the absorption and transmission of light by a sample. It involves shining a broad spectrum of light, ranging from ultraviolet (UV) to visible (Vis) wavelengths, through a sample and measuring the amount of light absorbed by the sample at each wavelength.

2. How does UV visible spectroscopy work?

This technique works by shining a light beam through a sample and measuring the intensity of the transmitted light. The sample absorbs certain wavelengths of light, which appear as dips or peaks in the spectrum. These unique absorption patterns can be used to identify and quantify the components present in the sample.

3. What is the range of wavelengths used in UV visible spectroscopy?

The range of wavelengths used in UV visible spectroscopy typically falls between 200-800 nanometers (nm), with the UV region ranging from 200-400 nm and the visible region ranging from 400-800 nm. However, the exact range may vary depending on the instrument and the type of sample being analyzed.

4. What are the applications of UV visible spectroscopy?

UV visible spectroscopy has a wide range of applications in various fields such as chemistry, biology, and materials science. It is commonly used to analyze the structure and composition of organic and inorganic compounds, monitor chemical reactions, and determine the concentration of a substance in a solution.

5. What are the advantages of UV visible spectroscopy?

One of the main advantages of UV visible spectroscopy is its simplicity and ease of use. It also requires minimal sample preparation and can provide quick and accurate results. Additionally, it is a non-destructive technique, making it ideal for analyzing delicate or valuable samples.

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