Question

A bottle of BACARDI Rum contains 750. ml of rum (40.0% alcohol, C2H5OH). If the density of the rum is 1.00 g/ml and Kf of water is 1.86 Cim, would the rum freeze in - 10 degree freezer? I

Answer 1

Bottle contains 40% alcahol (C2H5OH)

that is, water weight (w1) = 60 g

Alcahol weigt (w2) = 40 g

Molicular weigt of ethanol (M1) = 24+5+16+1 = 46 g

As the density of the solution is 1 g/ml , volume and weight are same.

also given Kf for water = 1.86

For the Depression in freezing point Colligative property we know,

$\Delta$Tf = Kf x w2 x 1000 / M2 x w1

There fore $\Delta$ Tf = 1.86 x 40 x 1000 / 46 x 60

= 27 0C.

It shows that there will be a depression in freezing pont 270C . We know that the water freeze at zero 0C .

Thus the container freez at -270C not at -10 0C.