Question

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A cell of path length 1cm contains 3.2x10-M solution of an
inorganic compound and having molar absorptivity 8500.
calculate the absorbance of solution?
A) 1.32
B) 3.56
C) 4.39
D) 2.72​

Answer 1

Answer:

. 0 COMSATS Institute of Information Technology, Abbottabad Course title and code Analytical Techniques Assignment number 01 Assignment title 10 Numericals of Beer–Lambert law Submitted by Zohaib HUSSAIN Registration number Sp13-bty-001 Submitted To Dr. Murtazaa SAYED. Date of submission Sunday, March 13, 2016

2. 1 1. A solution of Tryptophan has an absorbance at 280 nm of 0.54 in a 0.5 cm length cuvette. Given the absorbance coefficient of trp is 6.4 × 10 3 LMol-1 cm-1 . What is the concentration of solution? Solution: As ε = A / l c l= 0.5 cm A= 0.54 ε = 6.4 × 10 3 LMol-1 cm-1 C=? So c = A/ε l = 0.54 / 6.4 × 10 3 × 0.5 Answer = 0.000168 M 2. A solution of thickness 2 cm transmits 40% incident light. Calculate the concentration of the solution, given that ε = 6000 dm3 /mol/cm. Solution: A = 2 - log10 %T = 2 - log10 40 = 2 – 1.6020 = 0.398 A = ε l c l= 2cm ε = 6000 dm3/mol/cm A=0.398 c=? So c = A/ ε l = 0.398/ 6000 × 2 Answer = 3.316 X 10 – 5 mol / dm3

3. 2 3. A solution shows a transmittance of 20%, when taken in a cell of 2.5 cm thickness. Calculate its concentration, if the molar absorption coefficient is 12000 dm3/mol/cm. Solution: A = 2 - log10 %T = 2 - log10 20 = 2 – 1.301 = 0.698 A = ε l c l= 2.5 cm ε = 12000 dm3/mol/cm A=0.698 c=? So c = A/ ε l = 0.698/ 12000 × 2.5 Answer = 2.33 X 10 – 5 mol / dm3 4. Calculate the molar absorptivity of a 1 x 10 -4 M solution, which has an absorbance of 0.20, when the path length is 2.5 cm. Solution: A = ε l c l= 2.5 cm A= 0.20 C= 1 x 10 – 4 M ε =? So ε = A / l c