Jawaban:

Diketahui :

Kadar Mg(OH)₂ = 40%

Massa jenis = 1,2 gram/ml

Mr  Mg(OH)₂ = 58 gram/mol

Massa jenis = Massa / Volume

Ditanya : pH Mg(OH)₂

Penyelesaian :

Rumus Molaritas :

M = (Massa / Mr) × (1000 / Volume) × kadar

M = (Massa / Volume) × (1000 / Mr) × kadar

M = (Massa jenis) × (1000 / Mr) × kadar

M = (1,2 gram/ml) × (1000 / 58 gram/mol) × 40%

M = 8,276 M

Reaksi Ionisasi

Mg(OH)₂      ⇒      Mg²⁺      +      2 OH⁻

8,276 M            8,276 M           16,552 M

[OH⁻] = 16,552 M

p OH = - log [OH]

p OH = - log [16,552 M]

p OH = -1,21884              

(Nilai pOH tidak boleh berniali negatif, jika negatif maka nilai pOH = 0)

pH = 14 - 0

pH = 14 - 0

pH = 14

Mohon dikoreksi lagi