An aqueous solution of boric acid can be represented by the equilibrium system:
B(OH) ₃(aq) + 2 H₂O(l) ⇌ H₃O⁺(aq) + B(OH) ₄^-(aq) (K_a = 5.6 × 10^-10)
What is the pH of an eyewash solution which is 0.0018 M in boric acid?

Question

Quizplus · Accepted Answer

The pH is calculated using the formula pH = -log[H3O+]. For weak acids, [H3O+] can be approximated using the expression [H3O+] = √(Ka × [acid]). Substituting the given values, [H3O+] = √(5.6 × 10^-10 × 0.0018) ≈ 1.0 × 10^-6, giving a pH of approximately 6.00.

An Aqueous Solution of Boric Acid Can Be Represented by the Equilibrium