Questions and Answers
What does the term absorptivity represent in the context of light absorption?
In Beer's Law, which variable is inversely proportional to transmittance?
What is primarily measured in flow cytometry?
How is molar absorptivity defined mathematically?
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What phenomenon does chemiluminescence describe?
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Which aspect does a bandpass filter control?
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What distinguishes atomic absorption spectrophotometry from other methods?
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What basic principle do fluorometry and fluorescence depend on?
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In nephelometry, what is primarily measured?
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Which process is involved in bioluminescence?
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Study Notes
Key Terms in Light Absorption and Spectrophotometry
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Absorbance: Represents the light absorbed by a sample; mathematically expressed as log(1/T) or -log(T), where T indicates transmittance.
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Absorptivity: A constant that quantifies light absorption at a specific wavelength, defined for a 1 g/L concentration of a compound. Relation: a = Abc, with 'a' being absorptivity, 'A' absorbance, 'b' path length in cm, and 'c' concentration in g/L.
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Atomic Absorption (AA) Spectrophotometry: Technique where elements in a sample are atomized and measured based on their ability to absorb radiation when in a neutral state.
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Bandpass: The specific range of wavelengths that a filter or monochromator allows through, measured at half the peak transmittance.
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Beer's Law: Describes the linear relationship between concentration and absorbance; expressed as A = abc. States that higher concentration leads to increased absorption.
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Bioluminescence: Light emission due to an electron's return to a lower energy level following a biochemical reaction, enhanced by enzymes or photoproteins.
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Blank: A comparison solution in spectrophotometry that mirrors the test solutions except for the analyte being measured, ensuring accuracy in measurement.
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Chemiluminescence: Light emitted from an electron transitioning back down to a lower energy level, triggered by a chemical reaction, not light exposure.
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Electrochemiluminescence: Light emission resulting from an electrochemical reaction at an electrode's surface, also causing electrons to drop to a lower energy state.
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Flow Cytometry: A technique that analyzes physical or chemical characteristics of cells or particles as they flow individually through a measuring device.
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Fluorescence: Emission of light when a molecule absorbs light and re-emits it at a longer wavelength upon returning to the ground state, triggered by a photo excitation.
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Fluorometry: Method of measuring fluorescence emitted by substances, involving the detection of light after absorption and re-emission processes.
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Light: Energy form transmitted in electromagnetic waves, characterized by frequency and wavelength; consists of photons, whose energy inversely relates to wavelength.
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Light Scattering: Interaction of light with particles in a solution, causing a change in light direction due to this interaction.
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Molar Absorptivity: Similar to absorptivity but defined for a 1 mol/L solution, mathematically expressed as ε = Abc.
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Nephelometry: Method for detecting and measuring light scattered towards a detector not in the direct light path; often measures at right angles to the light beam.
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Description
Explore essential definitions related to absorbance and absorptivity in chemistry. This quiz will help you understand the relationship between light and concentration in various compounds. Test your knowledge of these fundamental concepts and their implications in scientific studies.
