Spectroscopic and Optical Methods Flashcards

1
Q

Define spectroscopy

A

absorption or emission spectrum

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2
Q

Define spectrophotometry

A

quantitative measurement of the absorption or emission

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3
Q

UV-Vis

A

Ultraviolet-Visible Spectrophotometry

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4
Q

FT-IR

A

Fourier-transform infrared sprectrophotometry

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5
Q

FAAS

A

Flame atomic absoption spectrophotometry

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6
Q

Refractometry

A

bending of light through media

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6
Q

Polarimetry

A

polarization (plane rotation) of light; for optically active compounds

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7
Q

Turbidimetry

A

scattering of light

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8
Q

Colorimetry

A

measurement of color variation

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9
Q

Common range of wavelength in UV-Vis

A

200 nm to 700 nm

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10
Q

Arrange in increasing wavelength

A

: Gamma, x, UV, visible, microwave, radio waves (FM, AM, long)

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11
Q

Main parts of spectrophotometer

A

Light source, monochromator, sample compartment, detector

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12
Q

Light source for UV and Visible

A

deuterium lamp for UV, tungsten lamp and gallium LED for visible

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13
Q

Sample compartment for UV and Visible

A

Quarts for UV, regular glass or polystyrene for visible

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14
Q

Subparts of monochromator

A

: entrance slit, dispersion device, exit slit

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15
Q

What is Beer-Lamber Law?

A

Relates concentration to absorbance: A = kbC = -log I/I0

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16
Q

T/F: Color absorbed is complementary to the color transmitted or reflected

A

: True

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17
Q

Concentration can be calculated from calibration curve if the ___ is known

A

absorbance

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18
Q

Calibration curve axes

A

y-axis: absorbance, x-axis: concentration

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19
Q

Calibration curve axes

A

y-axis: absorbance, x-axis: concentration

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20
Q

Calibration curve trend

A

Linear

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21
Q

Measurement must be made in the ___ for Beer’s law to apply

A

maximum absorption wavelength

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22
Q

Radiation must be ___ for Beer’s Law to apply

A

monochromatic

23
Q

Analyte must be ___ and ___ before and after absorption for Beer’s Law to apply

A

stable and chemically same

24
Q

____ solutions must be used since non-linearity is observed if not

A

Dilute

25
Q

An instrumental error that can lead to multiple wavelengths

A

polychromatic radiation

26
Q

An instrumental error that occurs when light is not from the source

A

stray light

27
Q

An instrumental error that can cause scattering and reflection

A

cuvette imperfection

28
Q

What chemical deviation can occur during spectrophotometry

A

degradation or change in analyte chemical structure

29
Q

Formula of refractive index

A

n = speed of light, c/velocity of light in medium, v

30
Q

Refractive index determines the ___ in medium

A

refraction of light

31
Q

Refractive index of air

A

n = 1

32
Q

Refractive index of water

A

n = 1.333

33
Q

Refractive index of diamond

A

n = 2.42

34
Q

Snell’s Law

A

n1 sin theta 1 = n2 sin theta 2

35
Q

Snell’s Law

A

n1 sin theta 1 = n2 sin theta 2

36
Q

Snell’s Law

A

n1 sin theta 1 = n2 sin theta 2

36
Q

Molar refraction formula

A

A = (M n^2 – 1)/(density n^2 + +2)

37
Q

Molar refraction of a binary mixture is the ____ and ____ of the pure components

A

sum of product of mole fraction and molar refractions

38
Q

Molar refraction is an ___ property

A

additive

39
Q

Molar refraction does not vary much with _____, but it is a strong function of _____

A

temperature; concentration

40
Q

Measurement of refractive index

A

Abbe refractometer and hand-held refractometer

41
Q

Electric and magnetic fields travelling perpendicularly across direction of propagation

A

Electromagnetic wave

42
Q

Fields (either the electric field or the magnetic field) are propagating in random orientation

A

Unpolarized light

43
Q

Some organic compounds (such as sugars) can ___ polarized light

A

rotate

44
Q

Specific rotation at temeperature and wavelength formula

A

Specific rotation = (optical rotation) / (path length) (concentration)

45
Q

Optical rotation and concentration relationship

A

directly proportional

46
Q

Optical rotation and concentration relationship

A

directly proportional

47
Q

Applications of spectroscopic and optical methods

A

characterization, determination of concentration

48
Q

If maximum absorbance wavelength is > ___; ____ the sample

A

1.5; dilute

49
Q

Blot refractometer prism with ___ and not paper or tissue

A

Kimwipe

50
Q

Adjust ____ using upper knob of refractometer; shadow must be sharp

A

dispersion

51
Q

Adjust ____ using lower knob; shadow must ____

A

refraction; fall on intersection crossed line

52
Q

levo-rotations: _____
dextro-rotations: _____

A

counterclockwise (left); clockwise (right)

53
Q

T/F: Higher alcohol-water concentration, higher refractive index

A

True

54
Q

refractive index of water ____ refractive index of alcohol

A

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