Calculate the H⁺ ion concentration in a solution with a pH of 3.85. A) 1.0 * 10^-4 M B) 1.4 * 10^-4 M C) 1.8 * 10^-4 M D) 2.2 * 10^-4 M E) None of the above

Question

Quizplus · Accepted Answer

To determine the ion concentration, we need to use the equation for the ionization of a weak acid: HA ⇄ H+ + A-. From this equation, we know that [H+] = [A-] since the acid is weak and does not fully dissociate. Since the pH of the solution is 3.85, we can calculate [H+] as 10^-3.85 = 1.78 x 10^-4 M. Therefore, [A-] = 1.78 x 10^-4 M. Now we can use the equilibrium constant expression for the ionization of H^{, which is Ka = [}][H+]/[H^{]. Plugging in the values we know, we get Ka = x^2/(1.78 x 10^-4), where x is the concentration of}. Since H^{is a weak acid, we can assume that x is small compared to 1.78 x 10^-4. Therefore, we can simplify the expression to Ka = x^2/1.78 x 10^-4. Rearranging, we get x = sqrt(Ka * 1.78 x 10^-4). Using the given value for Ka (1.2 x 10^-8), we can calculate x to be approximately 1.39 x 10^-5 M. This is the concentration of}, so the total ion concentration is [H^{] + [}] = 1.78 x 10^-4 M + 1.39 x 10^-5 M = 1.94 x 10^-4 M. This value is closest to choice B, 1.4 x 10^-4 M, so the answer is B.

Calculate the H+ Ion Concentration in a Solution with a PH

Calculate the H⁺ Ion Concentration in a Solution with a PH