1. During lab, a student used a Mohr pipet to add the following solutions into a 25 mL volumetric flask. They calculated the final volumes added, which are recorded below. The student then followed the directions in the manual to make the stock solution. Volumes Used to Create Stock Solution
Volume 0.200 M Fe(NO3)3 (mL) Volume 0.00200 M KSCN (mL)
Stock Solution 8.8 mL 2.06 mL
Using the stock solution above, the student made additional dilutions, with the final volumes below. Calculate the [FeSCN2+] in Standard 1. Report your answer in mM.

Volumes Used to Create Standard Solutions
Solution Volume Stock solution (mL) Volume Water (mL)
Standard 1 7.36 2.54
Standard 2 5.35 5.24
Standard 3 2.57 6.92
Standard 4 1.33 9.4
Note: Reporting your answer in mM is for grading purposes only. It is not necessary during lab. Report your answer to three places after the decimal.

2. Use the standard curve below to answer the following questions.

standard absorbance of FeSCN2+ as a function of its concentration. best fit line is y=3506.2x+0.0421. R squared = 0.9978

y = 3506.2x + 0.0421 R2 = 0.9978

Flag question: Question 6
Question 62 pts
A student prepared a solution that had 5.00 mL 0.002 M iron(III) nitrate in 1 M nitric acid, 3.00 mL 0.002 M potassium thiocyanate, and 2.00 mL DI water.

Using the standard curve above, if the absorbance for the solution was 0.37, calculate the equilibrium constant, Keq.

Note: If you set this up well in Excel, you can use the same spreadsheet in lab. Report your answer with zero places after the decimal.