pH & pKa (College Board AP Chemistry)

C₆H₅OH(aq) + H₂O(l)      C₆H₅O⁻(aq) + H₃O⁺(aq)          K_a = 1.12 × 10⁻¹⁰

Phenol is a weak acid that partially dissociates in water according to the equation

What is the pH of a 0.75 M C₆H₅0H(aq) solution?

For a certain reaction involving C₆H₅OH(aq) to proceed at a significant rate, the phenol must be primarily in its deprotonated form,  C₆H₅O⁻(aq). In order to ensure that the  C₆H₅OH(aq)  is deprotonated,  the reaction must be conducted in a buffered solution. On the number scale below, circle each pH for which more than 50 percent of the phenol molecules  are in the deprotonated  form (C₆H₅O⁻(aq)). Justify your answer.

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