Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

when performing the experiment a student wiped the finger prints from the curvet

ID: 1027629 • Letter: W

Question

when performing the experiment a student wiped the finger prints from the curvett When performing the experiment, a student wiped the fingerprints from the cuvette when the standards were measured in Part A, but left fingerprints on the cuvette when the absorbance of the test solutions were measured in Part B. a. How does this affect the absorbance reading of the s pectrophotometer? (Be specific.) b. Will the [Fe ] equilibrium concentration be too high or too low? Explain. c. Will the calculated Ke be too high or too low? Explain.

Explanation / Answer

If the student left the fingerprint on the working solution cuvettes but wiped it when using standards.

a. The absorbance values from the Part B section would be higher than actual value.

b. The Fe3+ equilibrium concentration thus obtained would be too low than actual value. Higher absorbance in Part B, means higher concentration of equilibrium [FeSCN2+], therefore when subtracted from initial [Fe3+], the equilibrium concentration [Fe3+] would be too low.

c. The calcualated Kc would be too high as now denominator is smaller for [Fe3+] value.