Question

1. A student mixes 5.00 mL 2.00 X 10~3 M Fe(NO3)3 with 5.00 mL2.00 X 10-3 M KSCN. She finds that in the equilibrium mixture theconcentration of FeSCN2+ is 1.20 X 10-4 M. Find Kc for the reactionFe3+(aq) + SCN-(aq) (arrows) FeSCN2 (aq).

Step 2. How many moles FeSCN2+ are in the mixture atequilibrium? What is the volume of the equilibrium mixture? (UseEq. 3.)

.

__________mL; ________moles FeSCN2+

How many moles of Fe3+ and SCN~ are used up in making theFeSCN2"1"?

.

__________moles Fe3+; _________moles SCN-

Step 3. How many moles of Fe3+ and SCN- remain hi the solutionat equilibrium? (Use Eq. 4 and the results of Steps 1 and 2.)

_______molesFe3+ ________molesSCN-

Step 4. What are the concentrations of Fe3*, SCN-, and FeSCN2+at equilibrium? What is the volume of the equilibrium mixture? (UseEq. 3 and the results of Step 3.)

[Fe3+] = _______M; [SCN-] =_________ M; [FeSCN2*] =_________M

mL

Step 5. What is the value of Kc for the reaction? (Use Eq. 2 andthe results of Step 4.)

Kc=_________