INSTRUMENTATION PROPER

Question 1

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

Answer 1

COLORIMETRY

Question 2

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

Answer 2

COLORIMETRY

Question 3

relies on visual acuity to determine end-point

Answer 3

Visual Colorimetry

Question 4

measurement of light intensity in a much narrower wavelength

Answer 4

SPECTROPHOTOMETRY

Question 5

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

Answer 5

SPECTROPHOTOMETRY

Question 6

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

Answer 6

diffraction gratings
monochromator
radiant energy

Question 7

measurements of light intensity of multiple wavelength

Answer 7

FILTER PHOTOMETRY

Question 8

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

Answer 8

FILTER PHOTOMETRY

Question 9

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.

Answer 9

Light
Monochromator

Question 10

PRINCIPLE of SPECTROPHOTOMETRY (LAW of COLORIMETRY):

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

Answer 10

Slits
narrow beam of light
chromatic purity

Question 11

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

Answer 11

light
absorption cell
radiant energy

Question 12

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

Answer 12

detector
electrical energy
meter or a digital read-out.

Question 13

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

Answer 13

BEER’S LAW

Question 14

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

Answer 14

concentration
directly proportional
light absorbed
inversely
logarithm of transmitted light

Question 15

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

Answer 15

%T

Question 16

Absorbance is directly proportional to the length of light path

Answer 16

BOUGUER’S LAW or LAMBERT’S LAW

Question 17

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

Answer 17

Absorbance
directly
length of light path

Question 18

What is Lambert’s Law formula?

Answer 18

A = abc

Question 19

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

Answer 19

BEER- LAMBERT LAW

Question 20

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

Answer 20

concentration
known path length
directly
absorption of light.

Question 21

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

Answer 21

proportionality constant or molar absorptivity or extinction coefficient

Question 22

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

Answer 22

length of light path in cm

Question 23

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

Answer 23

molar concentration of absorbing substance

Question 24

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

Answer 24

LIGHT SOURCE

Question 25

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

Answer 25

Tungsten Iodide lamp

Question 26

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

Answer 26

Quartz Halide lamp

Question 27

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

Answer 27

Deuterium Discharge lamp

Question 28

used above 800 nm

Answer 28

Infrared Energy source

Question 29

an electrically heated rod of rare earth element oxides

Answer 29

Merst glower

Question 30

uses silicon carbide

Answer 30

Globar

Question 31

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

Answer 31

Mercury Vapor lamp

Question 32

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

Answer 32

Hollow Cathode lamp

Question 33

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

Answer 33

ENTRANCE SLIT

Question 34

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

Answer 34

MONOCHROMATOR

Question 35

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

Answer 35

Monochromator bandpass

Question 36

used to hold the solution whose concentration is to be measures

Answer 36

ANALYTICAL / ABSORPTION CELL / CUVETTE

Question 37

for solutions that do not etch glass

Answer 37

Borosilicate glass

Question 38

does not absorb UV radiation at wavelength below 320 nm

Answer 38

Quartz or plastic

Question 39

good for 340 nm and above (visible region)

Answer 39

Alumina silica glass

Question 40

✓ 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

Answer 40

Prism

Question 41

✓ 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

Answer 41

Diffraction Gratings

Question 42

✓ 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

Answer 42

Transmission Filters

Question 43

✓ 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

Answer 43

Interference Filters

Question 44

measure light intensity by converting light signal into electrical signal

Answer 44

DETECTORS

Question 45

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

Answer 45

Barrier-Layer cell (Photocell or Photovoltaic cell)

Question 46

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 __________

Answer 46

semi-conductive metal layer electrons silver layer negative charge

Question 47

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

Answer 47

Photoemissive tube or Phototube

Question 48

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

Answer 48

Photoemissive tube or Phototube

Question 49

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

Answer 49

Photoconductive tube or Photoresistive tube

Question 50

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

Answer 50

Photoconductive tube or Photoresistive tube

Question 51

Does not require an external power source

Answer 51

Photoconductive tube or Photoresistive tube

Question 52

Capable of significantly amplifying a current

Answer 52

Photomultiplier tube

Question 53

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

Answer 53

Photomultiplier tube

Question 54

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

Answer 54

Photomultiplier tube