Cupric sulfate has a molar absorptivity of 2.81 M-1 cm-1 at max-635nm. 1. A cupr

Question

Cupric sulfate has a molar absorptivity of 2.81 M-1 cm-1 at max-635nm. 1. A cupric sulfate stock solution was analyzed in a spectrometer with a 1.0 cm pathlength cuvette. a. (2 pts) What is the molarity of a cupric sulfate stock solution if the absorbance was 0.880? b. (3 pts) What is the %T for the stock solution? c. (3 pts) What is the concentration of a second solution made by diluting 15.00 mL of the stock solution in a 25 mL volumetric flask? d. (2 pts) what is the absorbance and %T of the diluted solution? e. (2 pts) What is the absorbance of the diluted solution if the wavelength of the spectrophotometer was changed to 535 nm? f. (5 pts) Fill in the table below using data calculated above CuSO4 M Solution Stock Diluted %T 0.880 e. (3 pts) Write the Beer-Lambert equation for the data in the table above. A 2.81M-1cm-1 cuso4.0

Explanation / Answer

Q1.

apply beer law

A = e*l*C

A = absorbance of sample

e is the molar absorptivity , the typical units are 1/M-cm

l size of cuvette, typically reported in cm

c is the molar concentration, in mol per ltier or M

A = e*l*C

0.88 = 2.81*1*C

C = 0.88 /2.81

C = 0.313167 M

b)

%T from:

A = 2-log(T%)

10^-(A-2) = T%

T% = 10^-(0.88-2) = 13.18 %

c)

C1V1 = C2V2

0.313167 *15 = C2*25

C2 = 0.313167 *15/25

C = 0.18790 M

d

Tnew -->

A = 2.81*0.18790 = 0.527999

T% = 10^-(A-2) = 10^-(0.527999-2)

T% = 29.64

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