Calculate the pH of the following aqueous solutions. Choose your answer from the given pH ranges.0.1 M NaCN (pK_a for HCN = 9.31) A) pH 11.00-14.00 B) pH 3.00-5.99 C) pH 0.00-2.99 D) pH 6.00-8.99 E) pH 9.00-10.99

Question

Quizplus · Accepted Answer

NaCN is a salt that dissociates in water to form Na+ and CN-. The CN- ion is the conjugate base of HCN, a weak acid with a pKa of 9.31. When CN- is in solution, it can react with water to form HCN and OH- (hydroxide ions), making the solution basic. The pH of the solution can be estimated using the formula pH = 14 + 0.5(pKa - log[C]), where [C] is the concentration of the CN- ion. Substituting the given values, pH = 14 + 0.5(9.31 - log[0.1]) = 14 + 0.5(9.31 + 1) = 14 + 5.155 = 19.155. However, since the pH scale typically ranges from 0 to 14, a calculated pH greater than 14 indicates a very basic solution. Therefore, the correct pH range for a 0.1 M NaCN solution would be in the most basic range provided, which is pH 11.00-14.00.

Calculate the PH of the Following Aqueous Solutions