Analytical methods Chapter 5 Flashcards Preview

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Flashcards in Analytical methods Chapter 5 Deck (88)
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1

What is Spectrophotometric measurement?

It is a measurement of light intensity in a narrower wavelength

2

What is Photometric measurement?

It is a measurement of light intensity without consideration of its wavelength

3

Is described as photons of energy traveling in waves

Electromagnetic radiation

4

What is the formula of the Beer's law?

Concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light

5

What is the use of Light source?

Incident light for the system

6

What are the common source of light used near infrared regions?

Incandescent tungsten and Tungsten light bulb

7

What are the alternatives used for UV spectrum?

Deuterium discharge lamp and mercury arc lamp

8

What is the use of Entrace slit?

It minimizes the unwanted straylight

9

What is Straylight?

It is a wavelength outside the band which can affect the measurement and cause absorbance error

10

What is the use of monochromator?

It isolates specific or individual wavelength of light

11

Kinds of monochromator

Prisms, Diffraction gratings and Interference Filters

12

The principle of prism

A narrow beam of light focused on a prism is refracted as it enters the more dense glass

13

Most commonly used monochromator that consists of many parallel grooves

Diffraction gratings

14

Principle of constructive interference

Light waves enter one side of the filter and are refracted at the 2nd surface

15

What is the use of Exit Slit?

It controls the width of the light beam or band pass

16

The narrower the light beam

the greater the resolution

17

sample cell/ absorption cell/ analytical cell

cuvet

18

kinds of cuvet and some definition

Alumina Silica glass- simple/ older
Quartz/ Plastic- used for UV spectrum
Borosilicate glass- can stand increase temperature
Soft glass- Common glass

19

scatter light and should be discarded

scratches

20

Produces etching and dissolves glass

Alkaline solutions

21

What is a Photodetector?

It converts Light energy to Photoelectric Energy

22

Kinds of Photodetectors:

Photocell, Phototube and Photomultiplier tube

23

Requires external voltage and it gives off electron when light energy strikes it

Phototube

24

Simplest detector and no external voltage

Photocell

25

On a plate of iron covered with transparent layer of silver

Selenium

26

Most common type which can detect low level of light and amplifies radiant energy 200x

Photomultiplier tube

27

What is Sensitivity and Specificity?

Sensitivity is a term that can measure even the smallest movement of light while Specificity is a term that can only detect a specific light

28

It detects less amount of light and not as sensitive as photomultiplier tube

Phototransistors and Photodiode

29

moving needle on a dial or a digital display that indicates the amount of light passing

Galvanometer/ Ammeter

30

Splits the monochromator light into two components

Double-beam Spectrophotometer