Question

CHEM 114 ‐ Lab Experiment 7 Equilibrium I – Determination of an Equilibrium Constant

Test Solution	0.0020 M Fe(NO3)3 (in 0.10 M HNO3)	0.0020 M KSCN (in 0.10 M HNO3)	0.10 M HNO3
blank B	35 drops	0 drops	40 drops
1	35 drops	10 drops	30 drops
2	35 drops	20 drops	20 drops
3	35 drops	25 drops	15 drops
4	35 drops	30 drops	10 drops
5	35 drops	40 drops	0 drops

1- Explain why the five different combinations of reactants in part B should theoretically result in the same value for the constant K.

2. If the cuvette is not wiped clean, fingerprint smudges may be present during analysis.   

a. Explain how this error would affect the absorbance readingsfor FeSCN2+ in the analysis of the equilibrium solutions in part B (assume the error is not present during the standardization).

b. Would the value for K be too high, too low, or unaffected by this error? Explain.

Answer 1