Question

Question 1

Complete this prelab, and give this to your TA before prelab lecture starts. Please remember that this prelab is weighted and worth 15% of your lab grade! Total Points 30 1. Consider the following reaction: Starting with 4.00 mL of 0.200 M Fe (anej in a cuvette, 0.10 mL increments of 0.00100 M SCN (wa) will be added. Assume that because [Fe oal(SCN (wl, the [Fe(SCN)'] concentration can be calculated from the limiting reagent, SCN. Calculate [Fe(SCN)2"]. Report your concentrations to 2 significant figures. (1 point per correct concentration) V 0.00100 M KSCN (mL) 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 In the lab, we will measure the absorbance of the solutions in the table above and proceed to determine the slope in the plot of absorbance versus concentration. Suppose the plot is linear with an equation y 5500x If the absorbance of a is 1.320. What is [Fe(SCN)']? (4 pts) 2. R2 0.9999

Answer 1

ASSUMING COMPLETE REACTION IS TAKES PLACE

mole of Fe[SCN]⁺² = {Moles of SCN/2}/total volume in liters

V 0.001 M KCN ML	moles of KCN	Total volume ml	Fe{SCN}+2 (M)
0.1	0.000001	4.1	1.21951E-06
0.2	0.000002	4.2	2.38095E-06
0.3	0.000003	4.3	3.48837E-06
0.4	0.000004	4.4	4.54545E-06
0.5	0.000005	4.5	5.55556E-06
0.6	0.000006	4.6	6.52174E-06
0.7	0.000007	4.7	7.44681E-06
0.8	0.000008	4.8	8.33333E-06
0.9	0.000009	4.9	9.18367E-06
1	0.00001	5	0.00001

absorbance= 5500* concentration Fe[SCN]⁺²

1.32=5500*concentration of Fe[SCN]⁺²

^{concentration of} Fe[SCN]⁺²= 0.00024