Calculatate the mass of compound (molar mass = `256 g mol^(-1)` be the dissolved in 75 g of benzene to lower its freezing point by ` 0 .48 K(k_(f) = 5. 12 K kg mol ^(-1)` .

Answer

1.8g

Explanation

`Delta T_(f) = (k_(f)xx 1000 xx w_(B))/(w_(A) xx M_(B))`
` 0.78 = (5.12 xx 1000 xx w_(B))/(75 xx 256)`
` w_(B) = (0.48 xx 75 xx 256)/(5.12 xx 1000) = 1.8g`