SEM (Analytical techniques and Instrumentation, Pt 1) Flashcards
What made Spectrophotometry possible?
Monochromators
Visible light
a. <400 nm
b. 400 - 700 nm
c. > 700 nm
v
UV
a. <400 nm
b. 400 - 700 nm
c. > 700 nm
a
Infrared
a. <400 nm
b. 400 - 700 nm
c. > 700 nm
c
Color of infrared?
Red
Color of UV?
Violet
Relationship between wavelength and energy is Directly proportional
T or F
F
Inversely
The Wavelenth is long, the energy is low
this indicates?
a. Gamma
b. Radiowaves
Radiowaves (Infrared)
The Wavelenth is short, the energy is high
this indicates?
a. Gamma
b. Radiowaves
Gamma (Ultraviolet)
The concentration of a substance is directly proportional to the amount of light absorbed and is inversely proportional to the logarith of transmitted light
What is the law?
T or F
Beer-Lambert’s law
T
The formula for Beer’s law is:
A (Absorbance) = abc
What is “a”?
a. Molar absorptivity
b. Light path
c. concentration
a
The formula for Beer’s law is:
A (Absorbance) = abc
What is “c”?
a. Molar absorptivity
b. Light path
c. concentration
c
The formula for Beer’s law is:
A (Absorbance) = abc
What is “b”?
a. Molar absorptivity
b. Light path
c. concentration
b
Molar absorptivity and light path are constant
T or F
T
What is the standard value of light path?
1 cm
This correspond to the round cuvette
To compute the absorbance given the % transmittance:
a. A = 2- log %T
b. A = abc
c. A =2 + log %T
d. A = (Au x Cs) / As
a
What is the absorbance of Sodium in the cup with a transmittance of 45%?
0.3467
Solution:
A = 2 - log 45
= 0.3467
What is the percentage transmittance for Sodium if the absorbance is 0.69?
20%
Solution
%T = 10^(2-A)
&T = 10^(2-0.69)
= 20%
To determine the Cu (unknown analyte)
a. Cu = 2- log %T
b.Cu = abc
c. Cu = 2 + log %T
d. Cu = (Au x Cs) / As
d
Au = Absorbance of the unknown
Cs = Concentration standard
As = Absorbance standard
What is the Concentration of this Solution A if its absorbance is 0.420, comparing it to the concentration standard which is 69 with an absorbance standard of 0.911
31.81
Solution:
Cu = (Au x Cs) / As
Cu = (0.420 x 69) / 0.911
= 31.81
Blank is:
- distilled water
- Reagent
- Sample
that is used to subtract absorbance not due to analyte of interest
T or F
T
Blank sets the spectrophotometer to ___ absorbance
0
0 Absorbance = ______ transmittance
100%
Corrects the absorbance causd by the color of reagents
a. Reagent blank
b. Sample blank
a
Used to subtract the intrinsic absorbance caused by hemolysis, icterus, turbidity, or drug interference during sample analysis
a. Reagent blank
b. Sample blank
b
Use when the appearance of the sample is abnormal
a. Reagent blank
b. Sample blank
b
Used to zero the instrument before measuring test samples and other blanks
a. Reagent blank
b. Sample blank
a
Substance of known purity and concentration used to determine the concentration of the unknown analyte
a. Standard
b. Control
a
A solution containing various analytes with known target clues
a. Standard
b. Control
b