In preparing solution number 1 (see experimental procedure), a student measures
ID: 810442 • Letter: I
Question
In preparing solution number 1 (see experimental procedure), a student measures 5.0 mL of 2.00 x 10-3 M Fe(NO3)3, 2.0 mL of 2.00 x 10-3 M HSCN, and 3.0 mL of 0.50 M HNO3. (The solvent for the Fe(NO3)3 and HSCN solutions is 0.50 M HNO3). After combining these, what are the concentrations of Fe3+, HSCN, and H+ in the resulting solution? Show all work.
If, at equilibrium, the solution prepared in Problem #1 has an absorbance of 0.36, what is the Fe(SCN)2+ concentration, assuming that the absorptivity of Fe(SCN)2+ is 5150 L mol-1 cm-1 for 447-nm light?
For problem 1, I got 0.01M of Fe3+, 0.004 M of HSCN, and 0.154M of H+. How would I proceed with problem number 2?
Explanation / Answer
using Beer's Law, A = eCl
e = absorptivity of Fe(SCN)2+ = 5150 L mol-1 cm-1
A = 0.36
l = generaaly 1 cm
so, C = A/el = 0.36/(5150 x 1) = 6.99E-5