Calculate the vapor pressure at 50°c of a coolant solution that is 52.0:48.0 ethylene glycol-to-water by volume. at 50.0°c, the density of water is 0.9880 g/ml, and its vapor pressure is 92 torr. the vapor pressure of ethylene glycol is less than 1 torr at 50.0°c.

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Chemistry

Magdalena

25 April, 23:07

Calculate the vapor pressure at 50°c of a coolant solution that is 52.0:48.0 ethylene glycol-to-water by volume. at 50.0°c, the density of water is 0.9880 g/ml, and its vapor pressure is 92 torr. the vapor pressure of ethylene glycol is less than 1 torr at 50.0°c.

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Lucian Robles · Answer 1

If we use 100 mL of solution:

V (ethylene glycol - C ₂H₆O₂) = 0,52 · 100 mL = 52 mL.

V (water) = 0,48 · 100 mL = 48 mL.

m (C ₂H₆O₂) = 52 mL · 1,115 g/mL = 57,98 g.

n (C ₂H₆O₂) = 57,98 g : 62,07 g/mol = 0,934 mol.

m (H ₂O) = 48 mL · 0,988 g/mL = 47,424 g.

n (H ₂O) = 45,45 g : 18 g/mol = 2,635 mol.

mole fraction of solvent: 2,635 mol / (2,635 mol + 0,934 mol) = 0,73.

Raoult's Law: p (solution) = mole fraction of solvent · p (solvent).

p (solution) = 0,73 · 92 torr = 67,33 torr.