Join thousands of students who trust us to help them ace their exams!
Multiple Choice
Kc is 1.67 × 10^20 at 25°C for the formation of iron(III) oxalate complex ion: Fe3+(aq) + 3 C2O4^2-(aq) ⇌ [Fe(C2O4)3]^3-(aq). If 0.0100 M Fe3+ is initially mixed with 1.00 M oxalate ion, what is the concentration of Fe3+ ion at equilibrium?
A
0.0100 M
B
0.0200 M
C
1.00 × 10^-22 M
D
0.0050 M
0 Comments
Verified step by step guidance
1
Write the balanced chemical equation for the reaction: Fe^{3+}(aq) + 3 C_2O_4^{2-}(aq) ⇌ [Fe(C_2O_4)_3]^{3-}(aq).
Set up the expression for the equilibrium constant (K_c) for the reaction: K_c = \(\frac{[Fe(C_2O_4)_3^{3-}\)]}{[Fe^{3+}][C_2O_4^{2-}]^3}.
Define the initial concentrations: [Fe^{3+}]_0 = 0.0100 M and [C_2O_4^{2-}]_0 = 1.00 M. Assume the initial concentration of [Fe(C_2O_4)_3^{3-}] is 0 M.
Let x be the change in concentration of Fe^{3+} that reacts to form [Fe(C_2O_4)_3^{3-}]. At equilibrium, [Fe^{3+}] = 0.0100 - x, [C_2O_4^{2-}] = 1.00 - 3x, and [Fe(C_2O_4)_3^{3-}] = x.
Substitute the equilibrium concentrations into the K_c expression and solve for x: 1.67 \(\times\) 10^{20} = \(\frac{x}{(0.0100 - x)(1.00 - 3x)^3}\). Solve this equation to find the equilibrium concentration of Fe^{3+}.