Besarnya pH larutan HCN 0,1M (ka HCN= 4,9×10-10 adalah

[H+] = akar (Ka × M)
= akar (4,9 × 10^-10 × 10^-1)
= akar (49 × 10^-11 × 10^-1)
= akar (49 × 10^-12)
= 7 × 10^-6 M

pH = -log [H+]
= -log (7 × 10^-6)
= 6 - log 7

langsung aja y

HCN → H†CN`¹

[H†] = √ka×M
[H†] = √4,9×10^-10 × 0,1
[H†] = √49 × 10^-12
[H†] = 7 × 10^-6

pH = -log [H†]
pH = -log 7 × 10^-6
pH = 6 - log 7

semoga berguna +_+