37. Hitunglah pH larutan yang mengandung 100 mL asam sianida (HCN) 0,8 M dan 100 mL natrium sianida (NaCN) 0,2 M (Ka asam sianida = 4 x 10-5 )

Di ketahui: M HCN= 0.8 M
V HCN =100 Ml
M NaCN = 0,2 M
V NaCN= 100 Ml
( Ka HCN = 4×10^-5)
Di tanya : pH....??
Jawab : M HCN = M×V
= 0.8×100
= 80 mmol
M NaCN = M×V
= 0.2×100
= 20mmol
[H+] = ka× mol. Asam/mol. Garam
[H+] = 4×10^-5× 80/20
[H+] = 4×10^-5×4
[H+]=16×10^-5
pH= - log [H+]
= - log 16×10^-5
= 5-log 16
Semoga benar