Find the pH of a 0.183 M aqueous solution of hypobromous acid (HOBr), for which K_a = 2.06 × 10^-9. A) 4.712 B) 8.686 C) 0.738 D) 4.576 E) 9.288

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The pH of a solution is calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions in the solution. For weak acids like hypobromous acid (HOBr), we use the acid dissociation constant (Ka) to find [H+]. Given Ka = 2.06 × 10^-9 and the initial concentration of HOBr is 0.183 M, we can set up an ICE table to solve for [H+] at equilibrium. However, for weak acids with small Ka values, the change in concentration can be approximated as negligible compared to the initial concentration. Thus, [H+] ≈ sqrt(Ka × initial concentration of acid) = sqrt(2.06 × 10^-9 × 0.183) ≈ 1.94 × 10^-5 M. Then, pH = -log(1.94 × 10^-5) ≈ 4.712.

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