Spectrophotometer Flashcards

Questions and Answers

What is the wave-particle duality of light?

Light can exhibit properties similar to both waves and particles.

What defines light's particle property?

Light acts as a particle by conveying energy and being affected by gravity.

How does light travel from its source?

Light travels in waves.

What is the definition of wavelength?

The linear distance traveled by one complete wave cycle of electromagnetic radiation. Signup and view all the answers

What does the amplitude of a light wave determine?

The intensity of the light. Signup and view all the answers

Define frequency in the context of light.

The number of waves that pass a given point per unit of time. Signup and view all the answers

What is monochromatic light?

Light of one color, such as LED. Signup and view all the answers

What does polychromatic light mean?

Light of many colors, such as sunlight. Signup and view all the answers

What is selective absorbance?

The ability of a solution to absorb certain wavelengths of light while transmitting others. Signup and view all the answers

What does a spectrophotometer measure?

The intensity of light passing through a sample. Signup and view all the answers

What defines the electromagnetic spectrum?

A continuous range of radiation extending from gamma rays to radio waves. Signup and view all the answers

What is a nanometer?

One billionth of a meter. Signup and view all the answers

What is an angstrom?

One ten billionth of a meter. Signup and view all the answers

What is Beer's Law?

Absorbance (A) is directly proportional to Concentration (C). Signup and view all the answers

How is absorbance (A) mathematically defined?

Log 1/T. Signup and view all the answers

Under what conditions is A (absorbance) a constant?

Temperature, pH, solvent, incubation time, and same wavelength. Signup and view all the answers

What is a blank solution?

A solution consisting of all components except the compound being measured. Signup and view all the answers

What are the components of a spectrophotometer?

Light source, monochromators, prisms, diffraction gratings, sample cell, photodetectors. Signup and view all the answers

What is the purpose of a light source in a spectrophotometer?

To provide electromagnetic radiation. Signup and view all the answers

What are photodetectors used for?

To convert transmitted radiant energy to electrical energy. Signup and view all the answers

What are kinetic reactions?

Reactions that are convenient for quantifying enzymes by measuring catalytic activity. Signup and view all the answers

What is a continuous monitoring assay?

An assay where absorbance readings are taken at timed intervals. Signup and view all the answers

Study Notes

Properties of Light

Wave-particle duality describes how light exhibits properties of both waves and particles.
Particle property: Light acts as a particle that conveys energy and is affected by gravity.
Wave property: Light travels in waves; energy depends on wavelength.

Key Terms

Wavelength: Distance of one complete wave cycle of electromagnetic radiation (EMR).
Amplitude: Height of a wave that determines light intensity.
Frequency: Number of waves passing a point in a given time.

Light Characteristics

Monochromatic light: Light consisting of one color, e.g., LED.
Polychromatic light: Light made up of multiple colors, e.g., sunlight.

Principles of Absorbance

Selective absorbance: A solution's capacity to absorb specific wavelengths while transmitting others.
Spectrophotometer: An instrument to measure light intensity through a sample.

Electromagnetic Spectrum

A continuum of radiation from gamma rays to radio waves.
Ultraviolet range: Not visible, wavelengths from 220-380 nm.
Visible region: Wavelengths ranging from 380-700 nm.

Beer's Law

Absorbance (A) is directly proportional to concentration (C).
A = a * b * C, where 'a' is molar absorptivity, 'b' is the path length, and 'C' is concentration.
Deviations occur with non-monochromatic light, extreme concentrations, and solvent absorption effects.

Spectrophotometer Components

Light source provides EMR; common sources are incandescent tungsten lamps.
Monochromators isolate individual light wavelengths.
Types include glass colored filters and interference filters which allow selective wavelength passage.
Prisms and diffraction gratings are used to separate light into its component wavelengths.

Sample Handling

Sample cell (cuvette) holds test solutions and comes in various shapes.
Blank: A solution without the analyte used to zero the instrument.

Detection Methods

Photodetectors convert transmitted light to electrical energy; types include photocells and photomultiplier tubes.
Photomultiplier tubes are more sensitive than standard phototubes, amplifying the detected signal.

Reactions and Measurements

Kinetic reactions measure enzyme activity, useful for quantifying concentrations.
Fixed time methods stop reactions after a set period for measurement; continuous monitoring assays take regular absorbance readings over time.

Importance of Maintenance

Regular maintenance and function verification of the spectrophotometer are crucial for accurate results and adherence to Beer's law conditions.

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Description

Test your knowledge on the properties of light with these flashcards. The quiz covers key concepts such as wave-particle duality, particle properties, and wave properties of light. Ideal for students studying optics and related fields.