In the reaction: Fe^3+ + SCN^− ⇌ [Fe(NCS)]2+ The initial concentration of Fe^3+ was 0.109 and...

In the reaction:

Fe^3+ + SCN^− ⇌ [Fe(NCS)]2+

The initial concentration of Fe^3+ was 0.109 and the initial concentration of SCN^− was 0.105. After equilibrium was established, the concentration of the complex was 0.09. What is the equilibrium constant?

Expert Solution

Steps for calculating equilibrium constant are

Write the equilibrium expression for the reaction.
Determine the molar concentrations or partial pressures of each species involved.
Determine all equilibrium concentrations or partial pressures using an ICE chart.
Substitute into the equilibrium expression and solve for K

Fe ³⁺ + SCN⁻ ⇌ [Fe(NCS)]²⁺

Initial Concentration 0.109 0.105 0

Change in Concentration -x - x =x

Equilibrium Concentration 0.109- x 0.105- x 0.09

therefore x=0.09

Equilibrium Concentrations 0.109-.09 0.105-0.09 0.09

0.019 0.015 0.09

Hence, Equilibrium constant K_c = 0.09/0.019x0.015 = 315 or 3.15 x 10²

queen_honey_blossom answered 1 year ago

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