Question

The molar absorptivity of a dye is ε = 3.3 /M cm; what is the concentration of the solution (C) if the path length is given as ℓ = 1 cm and the absorption is A = 0.72? Beer-Lambert Law: A = εℓC SHOW WORK

(a) 0.33 M

(b) 1.4 M

(c) 0.22 M

(d) 0.72 M

Answer #1

The molar absorptivity, ε, for the dye called xylenol
blue (C23H22O5S, molar mass =
410.49 g mol-1) was found by experiment to be
8.15×103 L mol-1 cm-1 at 424 nm.
The percent transmittance of a 960 mL solution of xylenol
blue was determined to be 30.9%. If the path length of the
cell is 2.19 cm, determine the mass (in g) of xylenol blue
present in the solution. Report your answer to 3 significant
figures in scientific notation.

Assuming a molar absorptivity of 50,000 (Liters/mol cm)
calculate what molarity you would need to get an absorbance of 1.0,
using Beers Law.
A =ε c l, where A is the absorbance;
ε is the molar absorptivity in L/mol cm;
c is the concentration in mol/liter; and
l is the path length in cm, which, in our case, is
1.00 cm.
Algebraically rearranging gives c = A/ε l =A/ε.
B) Start with 20 mg of your dye. Calculate what morality...

Ergosterol, a precursor of vitamin D, has δmax = 282
nm and molar absorptivity ε = 11,900
M-1cm-1.
1). What is the concentration of ergosterol in a solution whose
absorbance A = 6.5×10-2 with a
sample pathlength l = 1.00 cm.
2). What is the absorbance of a solution having a concentration of
ergosterol of 5.2×10-5 M with a sample
pathlength l = 1.00 cm?

a.If a solution of a compound that has a molar absorptivity 45
M–1 cm–1 placed in a cuvette with a path length of 10 mm has an
absorbance of 0.65, what is the molarity of the compound in
solution? Show work.
b. What would the value of the equilibrium constant be for the
formation of FeNCS2+ from Fe3+ and SCN– , if the final equilibrium
concentration of [FeNCS2+] = 7.84 x 10–3 M when the solution
initially had [Fe3+] =...

Calculate the extinction coeffiction (ε, absorptivity) of each
compound using Beer-Lambert's Law ; A = εbc. Because of the small
amount of material used, you get 2 significant figures.
A = absorbance
ε = absorptivity
b = path length (1 cm)
c = concentration (moles/L)
My masses were 1.9mg (1), 2.3mg (2) and 2.1mg (3). The MW were
572.53 (1) , 486.35 (2) and 512.39 (3) . The max wavelength were
483.5nm = 0.452 (1) , 583 nm = 0.772...

By Beer’s Law, determine the molar absorptivity of the iron (II)
phenanthroline complex using maximum absorbance, the molar
concentration of the standard iron solution, and the cell path
length.
I'm confused because on this lab we have calculated the max
Wavelenth (497nm) and used a spectroscopy instrument to measue the
max Absorbance at that wavelength for the other samples and
unknown. Beers law seem simple, But how would I use it to find the
molar absorptivity?
SAMPLE (in ppm)
Max...

Given the absorbances and concentrations of
NO2-, calculate the molar absorbtivity
(cm-1?M-1)of this compound. Assume a 1.00 cm
path length. ( Hint: Need to construct a Beer's Law Graph)
Concentration (?M)
200
100
50
25
15
10
Absorbance
1.13
0.58
0.31
0.14
0.1
0.05

The visible ultraviolet spectrum of a solution of concentration
9.9 x 10-5mol.L a hydroxy-1-naphthoquinone natural origin was
obtained in an optical path cuvette 1 cm. In the wavelength
corresponding to 330nm, the compound showed absorbance equal to
0.320. To determine the concentration of a second solution of same
compound was obtained in the same conditions, a spectrum in 330nm
absorbance showed equal 0.480. In the conditions under which the
spectra of the samples were obtained conform to the Lambert-Beer
law....

Suppose 0.250 g of cobalt(II)
chloride hexahydrate is dissolved in 50.0 mL of 4 M HCl, and heated
to 80oC in a
cuvette having a 1.00-cm path length. At this temperature, the
percent transmittance of the solution at 690 nm is measured to be
48.0%.
What is the equilibrium
concentration of CoCl42- in the solution? (Hint: use Beer's
Law)
a. 2.10 × 10-2 M
b. 8.25 × 10-2 M
c. 1.81 × 103 M
d. 5.52 × 10-4 M
What...

The first-order decomposition of a colored chemical species, X,
into colorless products is monitored with a spectrophotometer by
measuring changes in absorbance over time. Species X has a molar
absorptivity constant of 5.00x103 cm–1M–1 and the path length of
the cuvette containing the reaction mixture is 1.00 cm. The data
from the experiment are given in the table below.
[X]
(M)
Absorbance (A)
Time (min)
?
0.600
0.0
4.00 x 10-5
0.200
35.0
3.00 x 10-5
0.150
44.2
1.50 x...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 4 minutes ago

asked 6 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 34 minutes ago

asked 39 minutes ago

asked 52 minutes ago

asked 56 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago