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Question 6 of 10 Try Again > Attempt 3 A standard solution of FeSCN2+ is prepared by combining 9.0 mL of 0.20 M Fe(NO3), with 1.0 mL of 0.0020 M KSCN. The equation for the reaction is as follows. Fe(NO3)3 + KSCN=FeSCN2+ + KNO, +2 NO; What allows us to assume that the reaction goes essentially to completion? The concentration of Fe(NO,), is much higher than the concentration of KSCN. The excess Fe* prevents the formation of the neutral Fe(SCN);. The reaction quotient Q is greater than Ke The equlibrium reaction has a very high Ke. Under the conditions given, Le Châtelier's principle dictates that the reaction shifts to the left. Based on that assumption, what is the equilibrium concentration of FeSCN equilibrium concentration of FeSCN2+ = 2.2222222 x10 SAMSUNG

Answer 1

The balanced equation for the formation of the complex [Ag(amine)]* is Fe+3 + SCN---------> FeSCN+2 Number of moles of Fe+3 = M*V = 0.20 M * 9.0 mL = 1.8 mmol Number of moles of SCN-= M*V = 0.0020 M * 1.0 mL = 0.002 mmol Since the concentration of Fe+2 is much higher than that of SCN-, assume that all SCN is converted to the complex. mmol Fe+3 + SCN FeSCN+2 Initial 1.8 0.002 Change -0.002 -0.002 + 0.002 Final 1.798 0 0.002 Total volume of the solution = 9.0 + 1.0 = 10.0 mL The conc. of amine remaining the solution = net moles/total volume = 5.0 mmol/75.0 mL = 0.066667 M Conc. of the complex formed = moles/total volume = 0.002 mmol/10.0 mL = 2.00 10-4 M. Concentration of the complex formed= 2.00 x 10-4 M