Chemical Technician Board Exam Reviewer

the study of the interaction between electromagnetic

radiation and matter

Spectroscopy

The type of energy that is transmitted through space at enormous velocities

Electromagnetic radiation

The length of the electrical vector at the maximum in the wave

Amplitude (A)

The linear distance between successive

maxima or minima of a wave

Wavelength (λ)

The number of oscillations of the

field per second

Frequency (n)

Postulate that electromagnetic radiation is made up

of packets of energy called

Photons/Quanta

Functional group that absorbs

light such as C=C, C=O, N=N, and N=O, having

multiple bonding

Chromophore

Functional group that does not absorb in the UV/VIS

region

Auxochromes

Unwanted light of wavelengths that differ from the target wavelength

Stray light

Influenced by instability of light source

Single-Beam Spectrophotometer

Not influenced by instability of light source

Double-Beam Spectrophotometer

Used for measurement in the ultraviolet region (190 to 350 nm)

D2 lamp

Used for measurement in the visible

region (350 to 900 nm)

Halogen lamp

Provide continuous source in the ultraviolet region

Deuterium/ Hydrogen Discharge Lamp

A spectrophotometer generally has an entrance ____ and an exit ____

slit

If the slit width is _______, the intensity of the light irradiating the sample increases but the resolution worsens.

increased

If the slit width is ______, the light intensity decreases but the resolution improves.

decreased

Wide range from 190 to 2500nm; Stable with most acids, bases, and organic solvents

Quartz/fused silica cuvette

Useful in the region of 350 - 2000 nm; Windows of good quality optical glass transmit well throughout the

visible range

Silicate glass cuvette

Disposable cells are molded from polystyrene methacrylate and other transparent plastics

Plastic cuvette

a type of semiconductor element that is used to convert light energy into electrical energy. It uses an electrical phenomenon called the "photovoltaic effect" whereby a reverse current proportional in size to the light intensity is created.

Photodiode

_______ spectroscopy is more suitable for characterization, but not for structural elucidation.

UV/Vis

_____ spectroscopy has taken a more important role in quantitation, rather than structural determination.

UV/Vis

Measured by transmittance method

Transparent liquid

Measured by transmittance or reflectance method (by integrating sphere)

Translucent liquid

Measured by reflectance method (by integrating sphere)

Opaque liquid

Measured by reflectance method (by integrating sphere or specular reflectance accessories)

Solid powder/coatings/mirrored surfaces

Only 1 calibration standard is prepared; Mainly applied to pass/ fail situation; No way to identify dilution error from the graph

Single point calibration

At least 2 calibration standards are needed; More accurate method; Easier to identify dilution error occur in one of the standards

Multipoint calibration

Perform serial dilution to obtain generally __ to __ calibration standards.

3 to 5

Perform spectrum scanning of standards to determine maximum absorption peak wavelength. Concentration of standards should fall between __ to __ absorption unit (depends on unit specs).

0 to 0.4

the derivatives of an absorbance with respect to the wavelength

Derivative spectroscopy

Used for measurement of diffuse and total reflectance, diffuse and total transmittance

Integrating Spheres (ISR)

Method for separating the solute from the stationary or mobile phase based on the difference in interaction

Chromatography

Birth of high performance liquid chromatography

1969

Localization of electrons within a molecule can cause molecules to have negative and/or positive poles.

Polarity

Stationary phase in Normal-Phase/Absorption Chromatography

High polarity

Mobile phase in Normal-Phase/Absorption Chromatography

Low polarity

Stationary phase in Reversed-Phase Chromatography

Low polarity

Mobile phase in Reversed-Phase Chromatography

High polarity

Chromatography method that separates compounds by molecular size (bulkiness)

Size Exclusion Chromatography