Advance Study Assignment Determination Of The Equilibrium Constant For A Chemical Reaction 1 A Student Mixes 5 00 Ml 2 1 (36.59 KiB) Viewed 54 times
Advance Study Assignment Determination Of The Equilibrium Constant For A Chemical Reaction 1 A Student Mixes 5 00 Ml 2 2 (39.11 KiB) Viewed 54 times
Advance Study Assignment: Determination of the Equilibrium Constant for a Chemical Reaction 1. A student mixes 5.00 mL 2.00 x 10 M Fe(NO), in 1 MHNO, with 3,00 mL.2.00 x 10 M KSCN and 2.00 mL of water. She finds that in the equilibrium mixture the concentration of FeSCN is 70 X 10M Find K for the reaction Fet (aq) + SCN (aq) Fe(SCN) (22) Step 1 Find the number of moles Felt and SCN initially present. (Use Eq. 3.) moles For moles SCN Step 2 How many moles of FeSCN are in the mixture at equilibrium? What is the volume of the equi- librium mixture? (Use Eq. 3.) mL moles FeSCN How many moles of Fe and SCN are used up in making the FeSCN moles Fel moles SCN Step 3 How many moles of Fel and SCN remain in the solution at equilibrium? (Use Eq 4 and the results of Steps 1 and 2.) moles Fe moles SCN Step 4 What are the concentrations of FeSCN and FeSCN at equilibrium? (Use Eq. 3 and the results of Step 2 and Step 3.) [F01 M. SCN) = M: [FeSONI M Step 5 What is the value of K for the reaction? (Use Eq 2 and the results of Step 4) K- (continued on following page)
2. Optional Assume that the reaction studied in Problem 1 isfel (aq) + 2 SCN (= FeSCN), (aq). Find for this reaction, given the data in Problem 1. .. Formulate the expression for K for the alternate reaction just cited K = b. Find K, as you did in Problem 1; take due account of the fact that two moles SCN are used up per mole Fe(SCN), formed as you carry out the following calculations Step 1 Results are as in Problem 1. Step 2 How many moles of Fe(SCN)," are in the mixture at equilibrium? (This will be the same as in Problem 1.) moles Fe(SCN), How many moles of Fe and SCN are used up in making the Fe(SCN);"? moles Fel moles SCN Step 3 How many moles of Fe and SCN remain in solution at equilibrium? Use the results of Steps ! and 2, noting that moles SCN at equilibrium = original moles SCN - (2x moles Fe(SCN);"). moles Fe moles SCN Step 4 What are the concentrations of Fe, SCN and Fe(SCN), at equilibrium? (Use Eq. 3 and the results of Step 30) [Fe] M: [SCN") = M: [Fe(SCN)"1 - M Step 5 Calculate K based on the assumption that the alternate reaction occurs. (Use the answer to Purt 2a.) K-
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