COLORIMETRY Flashcards
1
Q
Photons of energy travelling in waves.
A
ELECTROMAGNETIC RADIATION
2
Q
Photons means
A
Light
3
Q
Relationship between energy and wavelength is
described by __
A
Planck’s
4
Q
Relationship between energy and wavelength is
described by Planck’s
A
ELECTROMAGNETIC RADIATION
5
Q
What is the Planck’s formula
A
E=hv
6
Q
What is E in Planck’s formula
A
energy of photon (joules, EV)
7
Q
What is h in Planck’s formula
A
constant
8
Q
What is the h constant value
A
6.626 x 10-34 erg sec)
9
Q
What is the v in plancks
A
frequency
10
Q
What is frequency
A
number of vibration of wave
motion per second
11
Q
T/F
Frequency is directly proportional to energy
A
T
v=E
12
Q
distance between the middle line to the peak
A
Amplitude
13
Q
Other term for CREST
A
PEAK
14
Q
Important because it tells if light is visible or not
A
WAVELENGTH
15
Q
The distance between two successive peaks
(expressed in nanometer)
A
WAVELENGTH
16
Q
T/F
Wavelength is inversely proportional to frequency
A
T
↑W = ↓F
↓W = ↑F
17
Q
<400 nm
A
Ultraviolet region (UV)
18
Q
400-700 nm
A
visible spectrum (normal)
19
Q
> 700 nm
A
Infrared region (↓energy)
20
Q
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 350 - 430
Color absorbed?
Complementary Colors?
A
Violet……..Yellow - Green
21
Q
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 431 - 475
Color absorbed?
Complementary Colors?
A
Blue……Yellow
22
Q
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 476 - 495
Color absorbed?
Complementary Colors?
A
Green - Blue………..Orange
23
Q
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 496 - 505
Color absorbed?
Complementary Colors?
A
Blue - Green……….Red
24
Q
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 505 - 555
Color absorbed?
Complementary Colors?
A
Green……………..Purple
25
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 556 - 575
Color absorbed?
Complementary Colors?
Yellow - Green..........................Violet
26
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 576 - 600
Color absorbed?
Complementary Colors?
Yellow...................Blue
27
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 601 - 650
Color absorbed?
Complementary Colors?
Orange.............Green - Blue
28
COLORS AND COMPLEMENTARY COLORS OF VISIBLE SPECTRUM
Wavelength: 651 - 700
Color absorbed?
Complementary Colors?
Red..........Blue - Green
29
* The number of vibrations of wave motion per second.
FREQUENCY
30
COLOR WHEEL
Yellow
Violet
31
COLOR WHEEL
Orange Yellow
Blue-Violet
32
COLOR WHEEL
Orange
Blue
33
COLOR WHEEL
Red-Orange
Blue-Green
34
COLOR WHEEL
Red
Green
35
COLOR WHEEL
Violet Red
Yellow-Green
36
Most commonly used instrument for measurement of
analytes.
SPECTROPHOTOMETER
37
Measure the light intensity in a narrower wavelength
SPECTROPHOTOMETER
38
Determine the light transmitted by the solution
SPECTROPHOTOMETER
39
State the parts of Spectrophotometer in order
Light Source -> Entrance Slit -> Monochromator -> Exit Slit -> Sample cuvette -> PM tube -> A/D -> Display
40
Light Source is AKA ?
aka radiant source
41
Light source provides ____ light
polychromatic
42
Light with no specific wavelength
polychromatic light
43
Generates sufficient radiant energy to measure
the analyte of interest
LIGHT SOURCE
44
Two types of Light Source
Continuum Source
Line Source
45
Emits radiation that changes in intensity
Continuum Source
46
Examples of Continuum Source
Tungsten-Iodide Lamp
Deuterium Lamp
Xenon Discharge Lamp
47
◦ aka incandescent
◦ Provides light up to 1200 nm
◦ Can transport visible spectrum (15%)
and infrared region (the rest)aka incandescent
◦ Provides light up to 1200 nm
◦ Can transport visible spectrum (15%)
and infrared region (the rest)
Tungsten-Iodide Lamp
48
Emits light up to the UV region
(↓165nm)
Deuterium Lamp
49
Emits light in UV region and visible
region
Xenon Discharge Lamp
50
Emits limited radiation and wavelength
Line Source
51
Examples of Line Source
Mercury Arc Lamp, Sodium Vapor Lamp
Hollow Cathode Lamp
Light Amplification by Stimulated
Emission of Radiation (LASER)
52
An example of a Line source:
UV region and visible
Mercury Arc Lamp, Sodium Vapor Lamp
53
An example of a Line source:
Atomic absorption spectrophotometry
(AAS)
Hollow Cathode Lamp
54
An example of a Line source:
Light stimulation
Different types of LASER emit different wavelengths
Light Amplification by the Stimulated
Emission of Radiation (LASER)
55
5 IMPORTANT FACTORS IN LIGHT SOURCE
1. Range
2. Spectral Distribution within Range
3. Source of Radiant Production
4. Stability of Radiant Energy
5. Temperature
56
Prevents entrance of scattered light into the
monochromator
ENTRANCE SLIT
57
The entrance slit minimizes __
stray light
58
What is stray light
a light that does not come from
the light source
59
Aka unwanted light
Stray light
60
▪ Any wavelength outside the band
transmitted by the monochromator
▪ Most common cause of loss of linearity at
high-analyte concentration
Stray light
61
Isolate specific wavelength from the polychromatic
light emitted by the light source
MONOCHROMATOR
62
WHAT ARE THE 3 KINDS OF MONOCHROMATOR
Prisms, Diffraction gratings, filters
63
Wedge-shaped piece of glass, quarts or sodium
chloride
prisms
64
Can be rotated to allow only the desired
wavelength to pass through.
prisms
65
What is the downside of prisms
shorter wavelength are refracted
than longer wavelength
66
Made by cutting grooves (parallel grooves) or
slits into an aluminized surface of a flat piece of
crown glass
Diffraction Gratings
67
Wavelengths are bent as they pass a sharp
corner (diffraction).
Diffraction Gratings
68
o Are simple, least expensive, not precise but
useful
Filters
69
Bounces until isolate the desired wavelength
Filters
70
Filters are made by placing semi-transparent silver films on both sides of ______
dielectric
71
Give an example of dielectric
Magnesium fluoride (MgF)
72
Allows wide band of radiant energy and have
low transmittance of the selected wavelength
Filters
73
Give the three components of quality control
Wavelength Accuracy (important)
Dydimium (360nm) or Holmium oxide filter
(600nm)
Neutral density filters and dichromate solution
74
QUALITY CONTROL:
Check wavelength accuracy
Dydimium (360nm) or Holmium oxide filter
(600nm)
75
replace monochromator to check for accuracy
Dydimium (360nm)
76
Use to verify absorbance, accuracy, and
linearity
Neutral density filters and dichromate solution
77
Allow narrow fraction of specific wavelength to
pass through (desired wavelength)
EXIT SLIT
78
Exit slit controls the _________
width of light beam
79
total range of wavelength transmitted by
the monochromator
Bandpass:
80
What is accurate absorbance
bandpass of <1/5 the natural bandpass of the
spectrophotometer
81
Other names for Cuvet/Cuvette
Absorption cell, analytical cell, sample cell
82
Why does cuvet dissolve
when there’s a prolonged
contact with alkaline solution producing
scratches
83
Why is cuvet need to be discarded if there are scratches
Because it will scatters light
84
Purpose of cuvet/cuvette
It holds the solution to be measured.
85
WHAT ARE THE 4 KINDS OF CUVET
* Alumina Silica Glass
* Quartz/Plastic
* Borosilicate Glass
* Soft Glass
86
TYPE OF CUVET
used in 350-2000 nm
Most commonly used
From UV to IR
Alumina Silica Glass
87
TYPE OF CUVET
If the solution requires visible or ultraviolet
region
Quartz/Plastic
88
Convert light emitted into photoelectric energy
Intensity of transmitted light
PHOTODETECTOR
89
WHAT ARE THE DIFF KINDS OF PHOTODETECTOR
Photocell
Phototube
Photomultiplier tube
Photodiode
90
Other name for photocell
aka Barrier layer cell, photovoltaic cell
91
Simplest, least expensive, bu temperature
sensitive
Photocell
92
Composed of light-sensitive material (selenium
on an iron plate) covered with transparent layer
of silver
Photocell
93
Used in detecting radiation in the visible region
Photocell
94
What is the maximum sensitivity of photocell
550 nm
95
Contains cathode (rubidium or lithium) and
anode enclosed in glass case
Phototube
96
Photocell and Phototube is almost the same and only differs in ______
the energy source
97
o most commonly used
o Used in detecting visible and UV regions
o Has excellent sensitivity and rapid response
Photomultiplier Tube
98
Why is PM tube has excellent sensitivity and rapid response
Because it can detect very low levels of
light
99
PM tube is ___ more sensitive than phototube
200x
100
Has photocathode and dynodes which Burns when exposed to outside light
Photomultiplier Tube
101
With excellent linearity
o Most useful as a simultaneous multichannel
detecto
Photodiode
102
Displays output of the detection system
o Give out value generated by photodetector in
numbers
READ-OUT DEVICE
103
Give the three examples of READ-OUT DEVICE
* Galvanometer
* Ammeter
* Light-emitting diode (LED) display
104
what is BEER LAW
* “It states that the concentration of the unknown
substance is directly proportional to the absorbed
light (absorbance) and inversely proportional to the
transmitted light (% transmittance)."
105
BEER LAW
↑solute = ____
↓transmitted light
106
The amount of light absorbed
* Measured in spectrophotometry
ABSORBANCE
107
Proportional to the inverse log of transmittance
ABSORBANCE
108
ABSORBANCE is Mathematically derived from ?
%Transmittance
109
ABSORBANCE is expressed as
A = abc = 2 − log%T
110
Where a is:
absorptivity of light
111
Where b is:
length of light through the solution (light path)
112
Where c is:
concentration of solution
113
light path depends on ___
cuvet
114
the most common light path ofcuvet
1 cm
115
Ratio of radiant energy transmitted (T) divided by the
radiant energy incident of the sample (I)
T = transmitted light
o I = original wavelength
PERCENT TRANSMITTANCE (%T)
116
What is PERCENT TRANSMITTANCE (%T)
Ratio of radiant energy transmitted (T) divided by the
radiant energy incident of the sample (I)
117
%T measured by commercial spectrophotometers:
Ratio of sample transmitted beam divided by the
blank transmitted beam
118
correct absorbance; it follows the beer’s law
BLANKING TECHNIQUE
119
What are the two blanking techniques
REAGENT BLANK, SAMPLE BLANK
120
- used to correct absorbance caused by color of reagents (subtract)
REAGENT BLANK
121
measures absorbance of sample and reagent in the absence of the end-product (correct for interferences)
SAMPLE BLANK
122
Other name for flame photometry
a Flame Emission Photometry
123
It measures the light emitted by excited single atom
FLAME PHOTOMETRY
124
Atoms are excited through ____
FLAMES
125
What is the Principle of Flame Photometry
Excitation of electrons from lower to higher energy state
126
What is the Purpose of Flame Photometry
measurement of excited ions
127
Example of excited ions:
Na+
K+
Li+
128
What are the components of Flame Photometry
Light Source: Flame (is the cuvette)
Monochromator: Filter
Photodetector: Photocell
129
What is the METHOD of Flame Photometry
Indirect Internal Standard Method
130
What is the Internal Standard of Flame Photometry
Lithium or Cesium
131
Which is preferred in the internal standard in flame photometry?
Lithium
132
Correct variation in flame and AAS
characteristics
Internal Standard
133
Two types of SPECTROPHOTOMETER
SINGLE-BEAM SPECTROPHOTOMETER
DOUBLE-BEAM SPECTROPHOTOMETER
134
Simplest type
* Designed to make one measurement at a time at one
specified wavelength
SINGLE-BEAM SPECTROPHOTOMETER
135
The ______ of the analyte must be known in advance when a single-beam instrument is
used
absorption maximum
136
Type that splits monochromatic light into two
components
DOUBLE-BEAM SPECTROPHOTOMETER
137
DOUBLE BEAM
The _____ of the sample can be recorded
directly as the _____ of the sample beam
absorbance, electrical output
138
TYPES OF DOUBLE-BEAM SPECTROPHOTOMETER
DOUBLE-BEAM IN SPACE
DOUBLE-BEAM IN TIME
139
Has 2 photodetectors:
o sample beam
o reference beam
DOUBLE-BEAM IN SPACE
140
What are the 2 photodetectors in double-beam in space
sample beam, reference beam
141
Has one photodetector and alternately passes
the monochromatic light through the sample cuvet
and then reference cuvet using a chopper or rotating
sector mirror
DOUBLE-BEAM IN TIME
142
It measures the light absorbed by atoms dissociated
by heat.
ATOMIC ABSORPTION SPECTROPHOTOMETRY
(AAS)
143
Dissociate the element from its bond
* More sensitive than flame
ATOMIC ABSORPTION SPECTROPHOTOMETRY
(AAS)
144
Reference method for the measurement of
Magnesium and Calcium
ATOMIC ABSORPTION SPECTROPHOTOMETRY
(AAS)
145
AAS is a reference method for the measurement of ___ and ____
Magnesium and Calcium
146
What is the principle of AAS
element is not excited by merely
dissociated from its chemical bond and place in a
unionized, unexcited, ground state.
147
What is the PURPOSE of AAS
measurement of unexcited ions
148
Example of unexcited ions
(Ca2+ & Mg2+)
149
What are the components of AAS
Components:
o Light source: Hallow-cathode lamp
o Monochromator: diffraction gratings, prism
o Photodetector: photomultiplier tube
150
What is the interferences in AAS
Phosphate
151
How to interfere with phosphate
Add strontium or Lanthanum chloride
(chelates phosphate)
152
What is ZEEMAN EFFECT
The presence of intense static magnetic field will
cause the wavelength of the emitted radiation to split
into several components (shift in wavelength)
↑ static magnetic field = split to several components
153
The presence of intense static magnetic field will
cause the wavelength of the emitted radiation to split
into several components (shift in wavelength)
↑ static magnetic field = split to several components
ZEEMAN EFFECT
154
↑ static magnetic field = split to several components
ZEEMAN EFFECT
