What mass of salt (nacl) should you add to 1.80 l of water in an ice cream maker to make a solution that freezes at - 13.4 ∘c? assume complete dissociation of the nacl and density of 1.00 g/ml for water?

We will use this formula:

Δ T = i*Kf*C

when i = vant Hoff factor = 2

Kf = Constant 1.86 °C/m

and C = Concentration of molality

ΔT = 13.4 °C

So by substitution:

C = ΔT / (i*Kf)

= 13.4 / (2*1.86)

= 3.6 m

when molality = moles of solute / Kg of solvent

note molar mass of NaCl = 58.5 g / mol

∴mass of NaCl = 1.8 Kg * (3.6m NaCl / 1Kg) * (58.5 g / mol)

= 379 g