Question

Sometimes equilibria for complex ions are described in terms of dissociation constants, Kd. For the complex ion AlF₆³⁻, the dissociation reaction is:

a) AlF₆³⁻ ↔ Al³⁺ + 6F⁻
b) Al³⁺ + 6F⁻ ↔ AlF₆³⁻
c) Al³⁺ ↔ AlF₆³⁻ + 6F⁻
d) AlF₆³⁻ + 6F⁻ ↔ Al³⁺

Answer 1

The formation constant, Kf, for AlF6³- can be calculated by taking the reciprocal of the dissociation constant, Kd, but a numerical answer requires the specific Kd value. The equilibrium concentrations for other complexes are determined by using their respective dissociation constants and applying the equilibrium constant expression.The correct answer is option A.

Step-by-step explanation:

To calculate the value of the formation constant, Kf, for the complex ion AlF6³-, we start by understanding that the equilibrium constant expression for Kf is derived from the equilibrium equation for the formation of the complex ion from its constituents.

According to the equilibrium reaction AlF6³- ↔ Al³+ + 6F-, the formation constant, Kf, is defined as the concentration of products over the concentration of reactants, each raised to the power of their stoichiometric coefficients.

Since we're given the dissociation constant, Kd, which is the mathematical inverse of the formation constant, the formation constant can be calculated by taking the reciprocal of the dissociation constant. Without the actual value of Kd provided, it is not possible to give a numerical answer for Kf for AlF6³-.

The same principle applies for calculating equilibrium concentrations using a known dissociation constant; by applying the equilibrium constant expression and the initial conditions, we can solve for unknown concentrations.The correct answer is option A.