An aqueous solution containing 100.0 g of nacl and 100.0 g of cacl2 has a volume of 1.00 l and a density of 1.15 g/ml. the vapor pressure of pure water at 25 ∘c is 23.8 mmhg, and you can assume complete dissociation for both solutes

Question

Alia Gallegos

Chemistry

29 May, 20:17

An aqueous solution containing 100.0 g of nacl and 100.0 g of cacl2 has a volume of 1.00 l and a density of 1.15 g/ml. the vapor pressure of pure water at 25 ∘c is 23.8 mmhg, and you can assume complete dissociation for both solutes

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Sariah Hammond · Answer 1

Missing question: What is the vapor pressure of the solution at 25° C?

n (NaCl) = 100 g : 58,4 g/mol.

n (NaCl) = 1,71 mol.

NaCl → Na⁺ + Cl⁻, amount of ions are 2 · 1,71 mol = 3,42 mol.

n (CaCl₂) = 100 g : 111 g/mol = 0,9 mol.

CaCl₂ → Ca²⁺ + 2Cl⁻, amount of ions 3 · 0,9 mol = 2,7 mol.

m (solution) = 1000 ml (1,00 L) · 1,15 g/ml = 1150 g.

m (H₂O) = 1150 g - 100 g - 100 g = 950 g.

n (H₂O) = 950 g : 18 g/mol = 118,75 mol.

water's mole fraction = 118,75 mol : (118,75 mol + 2,7 mol + 3,42 mol).

water's mole fraction = 0,95.

p (solution) = 0,95 · 23 mmHg = 21,85 mmHg.