The acid-dissociation constant of hydrocyanic acid (HCN)at 25.0 °C is 4.9 × 10^-10. What is the pH of an aqueous solution of 0.080 mol L^-1 sodium cyanide (NaCN)?

Question

Quizplus · Accepted Answer

The correct answer is A because the pH of an aqueous solution of 0.080 mol L-1 sodium cyanide (NaCN) can be calculated using the dissociation constant of hydrocyanic acid (HCN) and the concentration of NaCN. The dissociation constant of HCN is 4.9 × 10-10, and the concentration of NaCN is 0.080 mol L-1. The pH of the solution can be calculated using the following equation:pH = -log[H+], where [H+] is the concentration of hydrogen ions in the solution.The concentration of hydrogen ions can be calculated using the dissociation constant of HCN and the concentration of NaCN. The dissociation constant of HCN is 4.9 × 10-10, and the concentration of NaCN is 0.080 mol L-1. The concentration of hydrogen ions can be calculated using the following equation:[H+] = (Ka * [NaCN]) / [HCN], where Ka is the dissociation constant of HCN, [NaCN] is the concentration of NaCN, and [HCN] is the concentration of HCN.The concentration of HCN can be calculated using the following equation:[HCN] = [NaCN] - [H+], where [NaCN] is the concentration of NaCN and [H+] is the concentration of hydrogen ions.The concentration of hydrogen ions can be calculated using the following equation:[H+] = (4.9 × 10-10 * 0.080 mol L-1) / (0.080 mol L-1 - [H+]), where 4.9 × 10-10 is the dissociation constant of HCN, 0.080 mol L-1 is the concentration of NaCN, and [H+] is the concentration of hydrogen ions.The concentration of hydrogen ions can be calculated using the following equation:[H+] = 4.9 × 10-10 mol L-1, where 4.9 × 10-10 is the dissociation constant of HCN.The pH of the solution can be calculated using the following equation:pH = -log(4.9 × 10-10 mol L-1), where 4.9 × 10-10 is the concentration of hydrogen ions.The pH of the solution is 11.11.

The Acid-Dissociation Constant of Hydrocyanic Acid (HCN)at 25