Question

1. ke dalam 500 mL air dilarutkan CH3COOK sebanyak 9,8 gram. Jika Mr CH3COOK = 98 dan ka CH3COOH = Hitunglah pH larutan tersebut!

Answer 1

Massa CH3COOK = 9,8 gr
Mr CH3COOK = 98
V = 500 ml = 0,5 liter

mol CH3COOK = 9,8 gr / 98 gr/mol = 0,1 mol
M CH3COOK = 0,1 mol / 0,5 liter = 0,2 M

[OH-] = √kw/ka  x M
[OH-] = √10⁻¹⁴/10⁻⁵  x 0,2
[OH-] = 1,4 x10⁻⁵

pOH = - log [OH-]
pOH = - log 1,4 x10⁻⁵
pOH = 5 - log 1,4

pH = 14 - pOH
pH = 14 - (5 - log 1,4)
pH = 9 + log 1,4
pH = 9 + 0,15 = 9,15