Final answer:
The pH of a 1.0 M solution of KCN can be calculated using the concentration of HCN and the dissociation constant (Ka) of HCN. The pH can be determined using the relationship -log[H+]. Given a Ka value of 6.2 x 10-10 and a concentration of 1.0 M KCN, the pH is calculated to be 5.10.
Step-by-step explanation:
The pH of a solution 1.0 M in KCN can be calculated using the relationship between the concentration of HCN and the dissociation constant (Ka) of HCN. The concentration of CN- ions can be used to calculate the concentration of H+ ions. Since HCN is a weak acid, the concentration of HCN can be approximated using the concentration of KCN.
Using the relationship:
pH = -log[H+], we can calculate the pH.
Given that Ka of HCN is 6.2 x 10-10,
[H+] = √(Ka * [HCN])
[H+] = √(6.2 x 10-10 * 1.0)
[H+] = √(6.2 x 10-10)
[H+] = 7.9 x 10-6
pH = -log(7.9 x 10-6)
pH = 5.10