Sebanyak 4 gram zat non elektrolit dilarutkan

Diket :

massa = 4 gram

p = 100 gram

Tb larutan = 100,347 °C

Tb pelarut (H2O) = 100 °C

Kb = 0,52 °C/m

Dit : Mr = ?

Jawab :

1. Cari besarnya molalitas (m)

Delta Tb = Tb larutan – Tb pelarut

Delta Tb = ( 100,347 – 100 ) °C

Delta Tb = 0,347 °C

Delta Tb = Kb × m

0,347 = 0,52 × m

m = 0,347 / 0,52

m = 0,667 molal

2. Cari Mr

m = (massa / Mr ) × (1000 / p)

0,667 = ( 4 / Mr ) × (1000 / 100)

0,667 = (4 / Mr) × 10

0,667 = 40 / Mr

Mr = 40 / 0,667

Mr = 60

Jawabannya B