Need help! 497m Vobume in l 20 x 10- olume in 200 x 10M ethl Npts in mm in ml Mi

Question

Need help!

497m Vobume in l 20 x 10- olume in 200 x 10M ethl Npts in mm in ml Misture KSON Standare Uknw 500 5.00 ×10"M 5.00 × 10 "M 5.00 If Method IIwas uod. [FeSCN: . | -× 10-. M: tleSCN, l in Mixtures l io 5 is found by liquation 7. Processing the Data A Caleulaton of K assuming the reaction This calculation is mast casily done by following Steps 1 through S in the dancussion Reswults are to be eniered in the table on the following pape. If you are using Excel. Fei.(aq) + SCN. (aq, ·FeSCN/.aq) set up the table as we have, and follow the directions below Step 1 Find the initial number of moles of Fe and SCN in the mixtures in test tobesI through 5. Use Equation 3 and enter the values in the first two columns of the table Step 2 Enter the experimentally detcrmined value o esCN eqlfor each of the mixtures in the nest so last column in the table. Uise Equation 3 to tind the number of moles of FeSCN in each of the mixtures, and emer the values in the fifth column of the table. Note that this is also the number of moles of Fe and SCN that were used up in the reaction continand n fowowing page

Explanation / Answer

b) Initial moles as same in part a) as given

Given that Equilibrium moles of Fe(SCN)-2 is half of equilibrium moles of Fe(SCN)2+. Therefore, equilibrium moles of Fe(SCN)-2 = 3*10^-4//2 = 1.5*10^-4 moles

In a), In mixture 1, Equilibrium Concentration of Fe(SCN)2+ = 1.5 *10^-4 mole Litre

Equilibrium mole = 3*10^-4 mole

Therefore, Liquid Volume available = 3*10^-4/(1.5*10^-4) = 2 Litres

Reaction is Fe3+ + 2 SCN- => Fe(SCN)-2

Therefore, 1 mole equivalent Fe3+ reacts with 2 mole equivalent 2 SCN- to give 1 mole equivalent Fe(SCN)-2

K = [Fe(SCN)-2]/([Fe3+]*[SCN-]^2)

In a) Practical value filled for [Fe(SCN)2+] is not correct, it should be different for different mixtures.

For different [Fe(SCN)2+, we will get different [Fe3+] & [SCN-]. Then We need to calculate K values and standard deviation. Same thing need to be performed for b).

Now since one equation can have one K value only, means Standard deviation should be zero. Therefore a) or b) whchever have minimum standard deviation is a more correct reaction and accordingly we will get correct formula for Fe(3+)Thiocyanate complex ion

Mixture Initial Moles Initial Moles Equilibrium moles Equilibrium moles Equilibrium moles Equilibrium Conc. Equilibrium Conc. Equilibrium Conc. Fe3+ SCN- Fe3+ SCN- Fe(SCN)-2 [Fe3+] [SCN-] [Fe(SCN)-2] K 1 20*10^-4 20*10^-4 18.5*10^-4 17*10^-4 1.5*10^-4 9.25*10^-4 8.5*10^-4 0.75*10^-4 112223 3 20*10^-4 20*10^-4 18.5*10^-4 17*10^-4 1.5*10^-4 9.25*10^-4 8.5*10^-4 0.75*10^-4 112223 5 20*10^-4 20*10^-4 18.5*10^-4 17*10^-4 1.5*10^-4 9.25*10^-4 8.5*10^-4 0.75*10^-4 112223

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.