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A student is using a Spec-20 to analyze the concentration of a solution. If the

ID: 507496 • Letter: A

Question

A student is using a Spec-20 to analyze the concentration of a solution. If the student measures the %T to be 52.6%, what is its absorbance? A 10-mL solution of CuCl_2 gives an absorbance reading of 0.30 au at a specific wavelength. Predict its solution its absorbance at the same wavelength if 50-mL DI water is added to this solution. Permanganate ion (MnO4-) is purple in color. Assume its calibration curve known and given below. If a KMnO4 solution has a % transmittance of 52.8%, what is its molarity concentration? Absorbance = (251.7 L middot mol^-1) times (Fe Concentration) + 0.0972 It is common to dilute stock solution to a specific concentration when it is used. How many mL of 6.0 M H_2SO_4 solution will be needed to prepare 10-L 0.1 H_2SO_4 solution? A sample of 0.300 mg pure chromium was added to excess hydrochloric acid to form a 10.0 mL aqueous solution of a chromium (III) salt, which has a violet hue. Exactly 1.00 mL of the resulting solution was analyzed using a spectrophotometer in a 1.00-cm cell at 575 nm, and the percent transmittance for the solution was 62.5%. What is the extinction coefficient? Include proper unit for extinction coefficient.

Explanation / Answer

A = Absorbance

% T = 52.6%

The relationship between absorbance and transmittance -

A = log10 1 / T

A = log10 100 / %T

A = 2 - log10 %T

A = 2 – log10(52.6)

A = 2 – 1.72

A = 0.28