i did the dillutions and got M2: 1.904E-04. i really don\'t know how to solve th

Question

i did the dillutions and got M2: 1.904E-04.
i really don't know how to solve the rest. Can you please help me?

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. Volume 0.200 M Volume 0.00200 M KSCN (mL) Fe(NO3l3 (mL) 9.06 mL Stock Solution 2.38 mL Using the stock solution above, the student made additional dilutions, with the final volumes below. Calculate the [FesCN21 in Standard 2. Report your answer in mM. SolutionVolume Stock solution (mL) Volume Water (mL) Standard 1 Standard 2 Standard 3 Standard 4 6.91 5.23 2.79 1.17 2.84 5.4 6.98 9.07 Note: Reporting your answer in mM is for grading purposes only. It is not necessary during lab

Explanation / Answer

Moles of Fe(NO3)3 used for stock solution = 0.2*9.06e-3

=1.812e-3mol

Moles of KSCN used fir stock solution = 0.002*2.38e-3

= 4.76e-6mol

Therefore the limiting reagent for the reaction is KSCN

Therefore,moles of FeSCN2+ = 4.76e-6

[FeSCN?2+] = 4.76e-6mol / 11.44e-3

Therefore,moles of FeSCN2+ in standard 2

= (4.76e-6mol / 11.44e-3 dm3)5.23e-3 dm3 = 2.1761e-6 mol

Therefore,

[FeSCN2+] in standard 2 = 2.1761e-6 mol/ 10.63e-3 dm3

=0.20471e-3 M

=0.20471e-6 mM

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