Question

It's January in Nashville and your local weather station just informed you that the temperature outside is

Answer 1

3.84 Kg of sodium chloride is needed to lower the freezing point of the water so that ice melts.

Explanation:

Data given:

mass of ice = 30 Kg

molar mass of NaCl = 58.5 grams/mole

ΔT(depression in freezing point) = 15.4 F  or - 9.22 degrees

Kf = 1.86 degree C/ mole

Molality = ?

mass of NaCl =?

i = 2 (because NaCl breaks into 2 ions)

ΔT = iKfm      equation 1

Depression in freezing point when ice melts, the temperature is 0 degrees so

the depression in temperature = 9.22 degrees

putting the values in the equation:

9.22 = 2 x 1.86 x $\frac{mass}{58.5}$ x$\frac{1}{30}$

mass = 3.84 kg of NaCl will be required to lower the freezing point of the water so that the ice melts.