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At 25°C, the dissociation constant of a base, BOH, is 1.0 x 10^-12. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be :

  1. A
    1.0 x 10^-6 mol L^-1
  2. B
    1.0 x 10^-5 mol L^-1
  3. C
    1.0 x 10^-8 mol L^-1
  4. D
    1.0 x 10^-7 mol L^-1

Solution & Step-by-step Explanation

The dissociation constant (Kb) of a base is given by the equation Kb = [BH^+][OH^-] / [BOH], where [BH^+] is the concentration of the conjugate acid, [OH^-] is the concentration of hydroxide ions, and [BOH] is the concentration of the base. For a weak base, the concentration of the base remains approximately constant, and if we assume [BH^+] = [OH^-] (since the base dissociates into equal amounts of BH^+ and OH^-), we can simplify the equation to Kb = [OH^-]^2 / [BOH]. Given Kb = 1.0 x 10^-12 and [BOH] = 0.01 M, we can solve for [OH^-]. Rearranging the equation gives [OH^-]^2 = Kb [BOH] = 1.0 x 10^-12 0.01 = 1.0 x 10^-14. Taking the square root of both sides, [OH^-] = √(1.0 x 10^-14) = 1.0 x 10^-7 M.

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At 25°C, the dissociation constant of a base, BOH, is 1.0 x 10^-12. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be :
A
1.0 x 10^-6 mol L^-1
B
1.0 x 10^-5 mol L^-1
C
1.0 x 10^-8 mol L^-1
D
1.0 x 10^-7 mol L^-1

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