What mass of salt (nacl) should you add to 1.48 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?

Question

Chemistry

Lara Burns

4 May, 15:05

What mass of salt (nacl) should you add to 1.48 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?

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Answers (1)

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Lennon Zamora · Answer 1

Answer is: mass of salt is 311,15 g.

V (H₂O) = 1,48 l · 1000 ml/l = 1480 ml.

m (H₂O) = 1480 g = 1,48 kg.

d (solution) = 1,00 g/ml.

ΔT (solution) = 13,4°C = 13,4 K.

Kf = 1,86 K·kg/mol; cryoscopic constant of water

i (NaCl) = 2; Van 't Hoff factor.

ΔT (solution) = Kf · b · i.

b (NaCl) = 13,4 K : (1,86 K·kg/mol · 2).

b (NaCl) = 3,6 mol/kg.

n (NaCl) = 3,6 mol · 1,48 kg = 5,328 mol.

m (NaCl) = 5,328 mol · 58,4 g/mol = 311,15 g.