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Cchm Lec > Analytical Method > Flashcards

Analytical Method Flashcards

1
Q

4 BASIC DISCIPLINES: ANALYTICAL
CHEMISTRY

A

Spectrometry = spectrophotometry, atomic absorption, and mass spectrometry

Luminescence = fluorescence, chemiluminescence, and nephelometry

Electroanalytic methods = electrophoresis, potentiometry, and amperometry

Chromatography = gas, liquid, and thin- layer

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2
Q

MEASUREMENTS OF RADIANT ENERGY

A

+ Emitted
+ Transmitted
+ Absorbed
+ Scattered
+ Reflected

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3
Q

There are two primary considerations in
every colorimetric analysis:

A
  1. Quality of the color
  2. Intensity of the color
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4
Q

COLORIMETRY 2 types

A

a. Visual Colorimetry
b. Photoelectric Colorimetry -

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5
Q

The primary analytical utility of spectrophotometry or filter
photometry is the isolation of discreet portions
of the spectrum for purposes of measurement.

A

Photoelectric Colorimetry

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6
Q

2 types: photoelectric measurement

A

Spectrophotometric measurement

Photometric measurement

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7
Q

light intensity in a narrower wavelength

A

Spectrophotometric measurement

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8
Q

light intensity at multiple wavelengths.

A

Photometric measurement

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9
Q

transmitted via electromagnetic waves that
are characterized by their frequency and Wavelength

A

Energy

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10
Q

distance between two successive
peaks and it is expressed in terms of nanometer (n)

A

Wavelength

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11
Q

Wavelength of visible spectrum

A

400-700m

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12
Q

Wavelength of ultraviolet (UV)

A

<400nm

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13
Q

Wavelength of infrared region (IR)

A

> 700nm

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14
Q

What is the Planck’s formula:

A

E = hv

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15
Q

E means

A

energy of a photon in Joules or constant (6.626
x 10^27 erg sec)

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16
Q

V means

A

frequency

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17
Q

number of vibrations of
wave motion per second

A

Frequency

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18
Q

Wave frequency: lower
Wavelength:

A

Longer

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19
Q

Wave frequency:
Wavelength: shorter

A

Higher

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20
Q

TYPES OF RADIANT ENERGY

A

+ Cosmic rays
+ Gamma rays
+ X-rays
+ Visible
+ Ultra-violet (UV)
+ Infrared (IR)
+ Radio, TV, microwave, etc.

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21
Q

measurement of the light transmitted ; determine the concentration

A

Spectrophotometer

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22
Q

concentration of a substance is directly
proportional to the amount of the light absorbed or inversely proportional

A

BEER’S LAW/ BEER-LAMBERT’S-LAW

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23
Q

ratio of the radiant energy transmitted

A

Transmittance

24
Q

amount of light absorbed

A

Absorbance

25
Q

Absorbance Mathematically derived from ________

A

%T

26
Q

A means

A

Absorbance

27
Q

a means

A

Molar absorptivity

28
Q

b means

A

Length of light (solution)

29
Q

c means

A

concentration of absorbing (solution)

30
Q

2 types of Spectrophotometer

A

Single beam spectrophotometer
Double-beam spectrophotometer

31
Q

• simplest type of absorption spectrometer
• one measurement at a time at one specified wavelength.
• single-beam instrument is used.

A

Single beam spectrophotometer

32
Q

• splits the monochromatic light into two components
• additional beam
• recorded directly as the electrical output

A

Double beam spectrophotometer

33
Q

2 Types of Double-beam
Spectrophotometer:

A

Double beam in space
Double beam in time

34
Q

2 photodetectors; sample beam and reference beam

A

Double beam in space

35
Q

one photodetector; sample of cuvet and sample of reference

A

Double beam in time

36
Q

7 basic components of single or double-
beam configuration spectrophotometer:

A
  1. Stable source of radiant energy
  2. Filter that isolates a specific region of the electromagnetic spectrum
  3. Cuvets
  4. Sample holder
  5. Radiation detector
  6. Signal processor and
  7. Readout device
37
Q

Parts of the Spectrophotometer: provides polychromatic light; intense beam of light is directed; must be linear.

A

Light/Radiant source

38
Q

2 types of light source

A

Continuum source

Line source

39
Q

Type of light source: changes in
intensity; widely used in the laboratory.

A

Continuum source

40
Q

Examples of continuum source

A

Tungsten, deuterium and xenon lamps

41
Q

light source in the
visible and near infrared region

A

Tungsten light bulb

42
Q

provide UV radiation in
analytic spectrometers.

A

Deuterium lamp

43
Q

source of radiation covers both the UV and the visible range

A

Xenon discharges lamp/ xenon lamp

44
Q

Type of light source: limited radiation and wavelength.

A

Line source

45
Q

Examples of line source

A

Mercury and sodium vapor lamp and hollow cathode lamp (AAS)

46
Q

Line source wide us in

A

Atomic absorption, molecular, and fluorescent spectroscopy

47
Q

used as light sources for spectrophotometry.

A

Light Amplification by Stimulated Emission of Radiation (LASER)

48
Q

Factors for choosing a light source:

A
  1. Range
  2. Spectral distribution within the range
  3. The source of radiant production
  4. Stability of the radiant energy and
  5. Temperature
49
Q

Alternatives for tungsten bulb:

A

+ Mercury arc (visible and UV)
+ Deuterium lamp (165nm) - UV
+ Hydrogen lamp - UV
+ Xenon lamp - UV
+ Merst glower -IR
+ Globar (silicone carbide) - IR

50
Q

• minimizes unwanted or stray light
• prevents the entrance of scattered light

A

Entrance slit

51
Q

• minimizes unwanted or stray light
• prevents the entrance of scattered light

A

Entrance slit

52
Q

• most common cause of loss of linearity
• limits the maximum absorbance
• causes absorbance error.

A

Stray light

53
Q

isolates specific or individual
wavelength

A

Monochromator

54
Q

isolates specific or individual
wavelength

A

Monochromator

55
Q

• wedge-shaped pieces of glass, quartz or sodium chloride
• can be rotated
• narrow light focused

A

Prism

56
Q

• the most commonly used kind monochromator
• made by cutting grooves (parallel grooves) or slits
• wavelengths are bent
• Produces linear spectrum
• light energy is absorbed by glass prism.

A

Diffraction gratings

57
Q

• the most commonly used kind monochromator
• made by cutting grooves (parallel grooves) or slits
• wavelengths are bent
• Produces linear spectrum
• light energy is absorbed by glass prism.

A

Diffraction gratings

Cchm Lec (5 decks)

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