Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Bchem 471 > Intro To Spec > Flashcards

Intro To Spec Flashcards

1
Q

Electromagnetic radiation consists of what fields and in which direction

A

Oscillating electric and magnetic fields that are perpendicular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the wavelength of visible light

A

700nm to 400nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is the Change in wavelength an order of 3 for each type of wave in the electromagnetic spectrum (radio waves, or waves, uv , etc.

A

Because of the wavelengths relationship to the speed of light (3x10^8m/s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Humans can only see a small part of the

A

Electromagnetic spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Equations for energy and energy per molecule

A

On cheat sheet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Does vocable light have enough energy to break typical chemical bonds

A

No, should be nondestructive

Slide 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is colour perceived as

What gives colour

A

The average of the wavelengths of light that is perceived by the eye

The light transmitted/reflected from a substance it what travels to our eyes and let us see a colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is chlorophyll green

A

This is because green light is not strongly absorbed by chlorophyll

This means it is instead transmitted and reflected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What implies that energy levels are quantized

A

The fact that only some frequencies of light are absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What has to happen for absorption to MAYBE occur

A

The change in energy between energy levels has the be equal to the energy of the photon

But other criteria has to be satisfied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Does absorption of a photon happen quick or slow

A

Quick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In uv/vis spec what nature of levels does the molecule change

What about IR

A

Electronic levels

Vibrational or rotational levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference in vibration and rotational levels vs electronic levels

A

vibration and rotational levels are closer together than electronically levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which transitions use mainly kinetic energy

A

Translational (moving in x y or z direction)

Rotational

Vibrational

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which transitions use mainly potential energy

A

Electronic

Nuclear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is the change in energy of an electronic transition greater or lower than that of a vibrational transition

A

Greater

17
Q

What is wave number proportional to

A

1/ wavelength

18
Q

What is the order from highest change in energy to lower for each transition

A

N E V R T

19
Q

What is an example of a electronic transition

Vibrational transition

A

Chlorophyll absorbing at 660nm and having a energy of 181kJ/mol

The vibrating aldehyde c=o in chlorophyll B at 1655cm-1

20
Q

What is an example of a electronic transition

Vibrational transition

A

Chlorophyll absorbing at 660nm and having a energy of 181kJ/mol

The vibrating aldehyde c=o in chlorophyll B at 1655cm-1

21
Q

What happens after a molecule gets excited

A

Can emit a photon (as either fluorescence or phosphorescence)

Can lose that energy

22
Q

What ways can molecules lose energy after being excited

A

Internal conversion (so losing heat)

Redox reaction (losing an electron)

Energy transfer (to another acceptor molecule)

23
Q

The lifetime of the excited state (time before energy is lost) is longer for fluorescence or phosphorescence

A

Phosphorescence

24
Q

The emmited photon has _____ energy than the excitation photon

A

Less

25
Q

Single beam absorption spec details

A

The monochromator scans across a wavelength region then only allows a specific wavelength of the incident light through

I0 is intensity from incedent light
If is intensity at detector (final instensity)

The I0 is measured with a blank to get absorbance when there is no sample

Only then can you measure sample

26
Q

Why are aqueous buffers used in measuring absorbace of samples

A

To keep the protien in a pH range that is works at

27
Q

Double beam absorption spec details

A

The I0 and If are measured at the same time through use of a beam splitter

The I0 is adjusted to equal If with solvent in both cuvettes (so that the Intensity of both are the same and can be easily compared)

The wavelength and path length for both cuvettes is the same

28
Q

What is special for the monochromater is double beam spec

A

Can automatically scan the wavelgngh region of interest

29
Q

What is the final output of a double beam spec

A

Log (I0/If) versus the wavelength

30
Q

For accurate absorbances measurements what should the absorbance be between

A

0.1 and 1.0

31
Q

When is absorbance less than zero

A

When the blank absorbs more than the sample

32
Q

What causes small changes in Absorbances

Large changes

A

Temp

Solvent used

Ph
Path length
Concentration of molecule
Molecule used

33
Q

Protiens are measured as

A

Percentage (w/v)

Or mg/ml

Slide15

34
Q

When there are two non interacting absorbing species what is their total absorbances equal to

A

The sun of the absorbance for both species

35
Q

Find absorbances and concentrations using the equations

A

Slides 16 and 17

Bchem 471 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions