INSTRUMENTATION PROPER Flashcards

1
Q

Measurement of the wavelength and the intensity of electromagnetic radiation in the visible region of the
spectrum.

A

COLORIMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Used for identification and determination of concentrations of substances that absorb light.

A

COLORIMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

relies on visual acuity to determine end-point

A

Visual Colorimetry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

measurement of light intensity in a much narrower wavelength

A

SPECTROPHOTOMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Makes use of prisms and/or diffraction gratings as monochromator to disperse the radiant energy into a
continuous spectrum & isolate radiant energy of desired wavelength

A

SPECTROPHOTOMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Makes use of prisms and/or ___________ as _________ to disperse the ______ into a
continuous spectrum & isolate radiant energy of desired wavelength

A

diffraction gratings
monochromator
radiant energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

measurements of light intensity of multiple wavelength

A

FILTER PHOTOMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

It makes use of filters (interference or transmission) to isolate part of the spectrum

A

FILTER PHOTOMETRY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

PRINCIPLE of SPECTROPHOTOMETRY (LAW of COLORIMETRY):

______ passes through a __________ to provide a selection of the desired region of the spectrum
to be used for measurements.

A

Light
Monochromator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

PRINCIPLE of SPECTROPHOTOMETRY (LAW of COLORIMETRY):

____ are used to isolate a __________ and to improve its __________.

A

Slits
narrow beam of light
chromatic purity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The _____next passes through an __________ where a portion of the ________ is absorbed, depending upon the nature and concentration of the solution.

A

light
absorption cell
radiant energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Any light not absorbed is transmitted to a _______, which converts the light energy to _________ that can be registered on a _____

A

detector
electrical energy
meter or a digital read-out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The concentration of the solution is directly proportional to the amount of light absorbed and inversely proportional to the logarithm of transmitted light

A

BEER’S LAW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

BEER’S LAW
The _______ of the solution is __________ to the amount of __________ and ________proportional to the __________

A

concentration
directly proportional
light absorbed
inversely
logarithm of transmitted light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ratio of the radiant energy transmitted, divided by the radiant energy incident on the sample

A

%T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Absorbance is directly proportional to the length of light path

A

BOUGUER’S LAW or LAMBERT’S LAW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

BOUGUER’S LAW or LAMBERT’S LAW:
___________ is _____ proportional to the _________

A

Absorbance
directly
length of light path

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Lambert’s Law formula?

A

A = abc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

the concentration of a solution for the known path length is directly proportional to its absorption of light.

A

BEER- LAMBERT LAW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

BEER- LAMBERT LAW
the _______ of a solution for the ________ is ____ proportional to its __________

A

concentration
known path length
directly
absorption of light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In the formula of Lambert’s law:
What ‘a’ stands for?

A

proportionality constant or molar absorptivity or extinction coefficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In the formula of Lambert’s law:
What ‘b’ stands for?

A

length of light path in cm

23
Q

In the formula of Lambert’s law:
What ‘c’ stands for?

A

molar concentration of absorbing substance

24
Q

provides a continuous spectrum of white light which can be separated at different wavelengths

A

LIGHT SOURCE

25
Q

produces energy wavelength from 340 – 700 nm (visible region); used
for moderately diluted solution

A

Tungsten Iodide lamp

26
Q

contains small amounts of halogen such as iodine to prevent the
decomposition of the vaporized tungsten from the very hot filament

A

Quartz Halide lamp

27
Q

– provides energy source with high output in the UV range (down to
165 nm)

A

Deuterium Discharge lamp

28
Q

used above 800 nm

A

Infrared Energy source

29
Q

an electrically heated rod of rare earth element oxides

A

Merst glower

30
Q

uses silicon carbide

A

Globar

31
Q

– emits narrow bands of energy at well-defined places in the spectrum
(UV and visible)

A

Mercury Vapor lamp

32
Q

consists of a gas-tight chamber containing anode, a cylindrical
cathode, and inert gas such as helium or argon

A

Hollow Cathode lamp

33
Q

isolates a narrow beam of radiant energy; prevents stray light from entering the monochromator

A

ENTRANCE SLIT

34
Q

wavelength selector; isolates radiant energy of desired wavelength and
excluding that of other wavelengths

A

MONOCHROMATOR

35
Q

the range of wavelengths transmitted and is calculated as width at
more than half the maximum transmittance.

A

Monochromator bandpass

36
Q

used to hold the solution whose concentration is to be measures

A

ANALYTICAL / ABSORPTION CELL / CUVETTE

37
Q

for solutions that do not etch glass

A

Borosilicate glass

38
Q

does not absorb UV radiation at wavelength below 320 nm

A

Quartz or plastic

39
Q

good for 340 nm and above (visible region)

A

Alumina silica glass

40
Q

✓ wedge-shaped pieces of glass, quartz, NaCl, or some other material that allows transmission of light
✓ Disperses white light into a continuous spectrum of colors by refraction
✓ Produces a non-linear spectrum. The longer wavelengths are close to each other and those of shorter
wavelengths are widely spaced.
✓ Glass prisms are for visible region while quartz prisms are for the UV region

A

Prism

41
Q

✓ consist of a thin layer of aluminum-copper alloy on the surface of a flat glass plate that has many small
parallel grooves ruled into the metal coating
✓ Rays of radiant energy bend (refract) around the sharp edges of the grooves
✓ Extent of refraction varies with the wavelength

A

Diffraction Gratings

42
Q

✓ colored glass or colored gelatin sandwiched between two glass plates
✓ Light outside the transmission band are absorbed by the colored material
✓ Band pass is 35 – 50 nm or more

A

Transmission Filters

43
Q

✓ Produce monochromatic light based on the principle of constructive interference of waves.
✓ dielectric material (e.g. NaF) sandwiched between two half-silvered pieces of glass
✓ The thickness of the layer determines the wavelength of energy transmitted.
✓ Band pass is 10 – 20 nm

A

Interference Filters

44
Q

measure light intensity by converting light signal into electrical signal

A

DETECTORS

45
Q

Composed of a film of light sensitive material (e.g. Selenium) on an iron plate with a transparent layer of silver

A

Barrier-Layer cell (Photocell or Photovoltaic cell)

46
Q

Barrier-Layer cell (Photocell or Photovoltaic cell):

When light passing through the _____________ falls upon the Selenium surface, ________
are released in proportion to the intensity of light and are collected to the ______ to produce a
__________

A

semi-conductive metal layer
electrons
silver layer
negative charge

47
Q

Has photosensitive material that gives off electrons when light energy strikes it

A

Photoemissive tube or Phototube

48
Q

Consists of 2 electrodes (cathode and anode) sealed in an evacuated glass

A

Photoemissive tube or Phototube

49
Q

A device whose electrical resistance decreases as the level of incident light is raised

A

Photoconductive tube or Photoresistive tube

50
Q

Cadmium sulfide or cadmium selenide are the light-sensitive materials typically used for the
visible region

A

Photoconductive tube or Photoresistive tube

51
Q

Does not require an external power source

A

Photoconductive tube or Photoresistive tube

52
Q

Capable of significantly amplifying a current

A

Photomultiplier tube

53
Q

The cathode is a negative light-sensitive metal that absorbs light and emits electrons in
proportion to the radiant energy that strikes the surface

A

Photomultiplier tube

54
Q
  • Electrons go to the dynodes, where electrons produce 4 – 6 additional electrons
  • The electrons are collected at a final electrode, the positive anode
A

Photomultiplier tube