Analytical Chemistry Chapter 2: Spectroscopy Overview

Spectroscopy is a technique that uses the interaction of electromagnetic radiation with matter (atoms, ions, and molecules) in quantitative and qualitative analysis.

The electromagnetic spectrum encompasses all electromagnetic waves arranged according to frequency and wavelength.

<p>Atomic spectroscopy and molecular spectroscopy (C)</p> Signup and view all the answers

<p>The Beer-Lambert law states that the absorbance of a solution is directly proportional to the concentration of the analyte and the path length of the light beam through the solution.</p> Signup and view all the answers

<p>The molar absorption coefficient ɛ is a constant that describes the ability of a substance to absorb light at a specific wavelength. It depends on the chemical nature of the analyte and the wavelength of light used.</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>The Beer-Lambert law has limitations, including deviation from linearity at high concentrations, changes in refractive index with concentration, and scattering of light by particles in the sample.</p> Signup and view all the answers

<p>To determine the concentration of analytes (D)</p> Signup and view all the answers

<p>Light source, monochromator, sample holder, detector, and readout (A)</p> Signup and view all the answers

<p>Tungsten filament lamp, deuterium lamp, and xenon arc lamp (A)</p> Signup and view all the answers

<p>Prisms and gratings (C)</p> Signup and view all the answers

<p>Single beam and double beam (A)</p> Signup and view all the answers

<p>Versatility, high sensitivity, and high selectivity (B)</p> Signup and view all the answers

<p>UV-Vis spectroscopy has numerous applications in various fields, including pharmaceutical analysis, environmental monitoring, food science, and clinical chemistry.</p> Signup and view all the answers

Spectroscopy analyzes the interaction of electromagnetic radiation (EMR) with matter (atoms, ions, and molecules) to identify and quantify substances.

The electromagnetic spectrum is a range of all electromagnetic radiation, arranged by frequency and wavelength.

Wavelength (λ) represents the distance between identical points on successive waves. Frequency (ν) describes the number of waves passing a point in one second. Amplitude measures the wave's height from the midline.

Photons are discrete packets of energy that make up electromagnetic radiation. The higher the frequency of the radiation, the more energy each photon has.

Absorption occurs when atoms or molecules gain energy and transition to higher energy levels. Emission involves excited atoms or molecules releasing energy and returning to lower levels.

Atomic spectroscopy analyzes atoms in the gas phase, while molecular spectroscopy examines molecules in solutions.

The Beer-Lambert Law states that the absorbance of a solution is directly proportional to its concentration and the pathlength of the light beam through it.

The molar absorption coefficient (ε) is a measure of how strongly a substance absorbs light at a specific wavelength.

UV-Vis spectroscopy uses ultraviolet and visible light to analyze substances based on their absorption patterns.

Quantitative analysis determines the amounts of specific substances in a sample.

A calibration curve plots absorbance versus concentration for a known set of standards. This curve is used to determine the concentration of an unknown sample.

A spectrophotometer is an instrument that measures the absorbance and transmittance of light through a sample.

A monochromator is a device that separates light into its individual wavelengths and allows a specific wavelength to pass through the sample.

A cuvette is a small container holding the sample being analyzed in a spectrophotometer.

A detector converts light energy into an electrical signal that can be measured by the spectrophotometer.

A single beam spectrophotometer uses a single beam of light that passes through both the sample cell and the reference cell.

A double beam spectrophotometer uses two beams of light, one passing through the sample and the other through the reference or blank.

A filter monochromator allows only a specific range of wavelengths to pass through by using filters.

A prism monochromator separates light into its component wavelengths by using a prism.

A grating monochromator uses a diffraction grating to separate light into its wavelengths.

The deviation from Beer-Lambert's Law can occur due to factors like high concentration or changes in the solution's refractive index.

Dilution is a simple solution to avoid deviations from Beer-Lambert's Law, as it reduces the concentration.

UV-Vis spectroscopy is a highly sensitive technique, allowing detection of substances at very low concentrations.

UV-Vis spectroscopy is selective, meaning it can distinguish between different substances with distinct absorption spectra.

UV-Vis spectroscopy is accurate, providing reliable measurements and quantifications of substances.

UV-Vis spectroscopy can be automated, making it efficient for analyzing large numbers of samples.

Interferences in UV-Vis spectroscopy can arise from factors like the presence of other absorbing substances or deviations from Beer-Lambert's Law.

Solutions to overcome interferences include techniques like extraction to isolate the analyte or dilution to reduce concentration.