Jawabanmu

2014-03-11T19:56:39+07:00
2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l)

Mol H2SO4 = V x M
Mol H2SO4 = 20 mL x 0,2
Mol H2SO4 = 4 mmol

Mol NaOH = 2 x mol H2SO4
Mol NaOH = 2 x 4
Mol NaOH =  8 mmol (25 mL larutan NaOH)

Dalam 100 mL larutan NaOH terdapat :

Mol NaOH = 100 mL : 25 mL x 8
Mol NaOH = 4 x 8
Mol NaOH = 32 mmol

Massa NaOH = 32 mmol x 40
Massa NaOH = 1280 mg = 1,28 gram

Kadar NaOH dalam cuplikan = 1,28 : 6,4 x 100%
Kadar NaOH dalam cuplikan = 20%