PHAN LAB FINALS 2

Question 1

It is a method of analysis that deals with the measurement of spectra.

Answer 1

Spectrometry

Question 2

It is a branch of spectrometry that embraces the measurement of the absorption by chemical species of radiant energy

Answer 2

SPECTROPHOTOMETRY

Question 3

It is the distance between two consecutive peaks or
crests

Answer 3

Wavelength

Question 4

What are the ranges of wavelengths

Answer 4

UV 220 – 380 nm
Visible 380 – 780 nm
Near IR 780 – 3000 nm
Medium IR 3.0 – 15 um
Far IR 15 – 300 um

Question 5

It is the number of waves passing through any point
per second.

Answer 5

Frequency (n)

Question 6

Principles of wavelengths

Answer 6

Every substance absorbs or transmits certain wavelengths of radiant energy but not other wavelengths.

The intensity of the transmitted radiant energy is a function of the concentration.

Question 7

Components of a colorimeter

Answer 7

Light Source
Condenser
Monochromator (Prism)
Slit
Sample Holder (Cuvette)
Detector (Photocell)
Display

Question 8

It is the ratio of the amount of light transmitted to the amount of light that initially fell on the surface.

Answer 8

Transmittance

Question 9

It is the negative logarithm of transmittance.
Absorbance and transmittance bear an inverse relationship.

Answer 9

Absorbance

Question 10

This law states that the power of a TRANSMITTED radiant beam DECREASES exponentially as the CONCENTRATION of the solution containing the absorbing chemical species increases
arithmetically.

Answer 10

Beer’s Law

Question 11

This law states that the power of a TRANSMITTED radiant beam DECREASES exponentially as the THICKNESS of the solution containing the absorbing chemical species increases arithmetically.

Answer 11

Lambert’s / Bouguer’s Law

Question 12

This law is a combination of the the two laws and relates the power of the incident and the transmitted radiant beam to the thickness and concentration of the solution

Answer 12

Beer-Bouguer’s Law
Beer-Lambert

Question 13

Wave length of UV Region

Answer 13

100nm - 400 nm

Question 14

Wavelength of Visible Region

Answer 14

400nm - 750nm

Question 15

The light source for UV - VIS

Answer 15

tungsten filament lamps and hydrogen-deuterium
lamps are the most widely used and suitable light sources as they cover the whole UV region.

Question 16

UV instrumentation that is composed of prisms and slits

Answer 16

Monochromator

Question 17

Instrumentation made of either silica or quartz. Glass can’t be used for the cells as it absorbs light in the
UV region.

Answer 17

Sample and reference cells

Question 18

Instrument that is generally, two photocells serve the purpose of the detector in UV spectroscopy.

Answer 18

Detector

Question 19

Instrument that amplify the signals many times to get a clear and recordable signal.

Answer 19

Amplifier

Question 20

Instrument that stores all the data generated and
produces the spectrum of the desired compound.

Answer 20

Recording Device

Question 21

Light source for UV Spectrometry

Answer 21

1. Hydrogen-deuterium lamp
2. Mercury lamp

Question 22

Light Sources for VIS spectrometry

Answer 22

Tungsten Lamp

Question 23

Applications of UV-VIS

Answer 23

1. Detection of impurities
2. Quantitative determination of compounds that absorb UV radiation
3. Study of kinetics of reactions
4. Drug and raw materials assay