1.
please explain your answers.
1) In a solution, when the concentrations of a weak acid and its conjugate base are equal, A) the
system is not at equilibrium. B) the buffering capacity is significantly decreased. C) the -log of
the [H+] and the -log of the Ka are equal. D) all of the above are true. 2) Of the following
solutions, which has the greatest buffering capacity? A) 0.821 M HF and 0.217 M NaF B) 0.821
M HF and 0.909 M NaF C) 0.100 M HF and 0.217 M NaF D) 0.121 M HF and 0.667 M NaF E)
They are all buffer solutions and would all have the same capacity. 3) The molar solubility of A)
Na3PO4 B) NaF C) KNO3 D) ACI3 E) Mns is not affected by the pH of the solution.
Solution
Ans 1 : C) the -log of the [H+] and the -log of the Ka are equal
The solution that contains weak acid and conjugate base , resists any change in the pH of the
solution if any strong acid or base is added to it. Such a solution is called as buffer. Here in the
buffer -log of [H+] represents the acidity , which is equal to the -log of its acid dissociation
constant.