Experiment J: Introduction To Spectroscopy

Question 0

Qualitative spectroscopy tries to:

Answer 0

Determine what is in a sample by looking at the overall line shapes, intensities, and wavelengths at which they occur

Question 1

Spectroscopy is the study of:

Answer 1

The interaction of electromagnetic radiation with a chemical species

Question 2

Quantitative spectroscopy tries to:

Answer 2

determine how much of a fine component is present in a mixture

Question 3

What form is the spectroscope measurements presented in?

Answer 3

A spectrum- a graph of the amount of radiation NOT absorbed or the amount absorbed as the y-axis and some function of the light energy as the x-axis

Question 4

If the incident radiation is I(not) and the intensity after the passage through the sample is I, then the amount transmitted is defined by the equation:

Answer 4

T = I/ I(not)

Question 5

The percent transmittance can be represented in the equation:

Answer 5

T%= 100x (I/I(not))

Question 6

Absorbance is measured through the calculation

Answer 6

A=log10 ( 1/T)

Question 7

The most common types of spectroscopy in undergraduate courses are:

Answer 7

UV-vis (ultra violet visible)
IR (infrared)
NMR (nuclear magnetic resonance)

Question 8

Describe UV-vis?

Answer 8

• can be used both quantitatively and qualitatively
• rarely just qualitative
• if you know what’s in the sample it can be used to determine how many of those molecules are present

Question 9

Describe IR

Answer 9

• used mostly qualitatively to give information about the structure of a molecule
• causes molecule to vibrate and specific functional groups tend to absorb the radiation at characteristic wavelengths

Question 10

Describe NMR

Answer 10

• uses radio frequency light and is primarily used to deduce the structure of molecules and very rarely for quantitative purposes
• essentially element specific
• depends on the interaction of the spin if the nuclei of the molecules with magnetic fields

Question 11

The number of peaks in a group (multiplicity) might indicate the _____________ attached to an adjacent atom

Answer 11

The number of protons

Question 12

The area under the peaks in a group is related to the

Answer 12

Number of protons connected to the same atom (same environment)

Question 13

Transmittance ______ with increasing concentration

Answer 13

Decreases

Question 14

Absorption ________as concentration increases

Answer 14

Increases

Question 15

What is the equation for the Beer-Lambert Law

Answer 15

A= (molar absorptivity) (path length) (concentration)

Question 16

In solids parts per million is a ___-___ ration

Answer 16

Mass to mass

1ppm= 1x10^-6 g

Question 17

In liquid samples ppm is usually cited as ___-____

Answer 17

Mass to volume

Ppm =mass of additive in mg per litre of the liquid sample