Multiple Choice
An ethylene glycol solution contains 25.2 g of ethylene glycol (C2H6O2) in 99.5 mL of water. Determine the change in boiling point. Assume a density of 1.00 g/mL for water.
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13. Solutions
Boiling Point Elevation
Multiple Choice
Pure water boils at 100ºC. What is the new boiling point of water after the addition of 13.12 g aluminum chloride, AlCl3, to 615 g water?
A
100.25°C
B
100.08°C
C
100.33°C
D
100.16°C
Verified step by step guidance1
Determine the molality of the solution. First, calculate the moles of aluminum chloride (AlCl3) using its molar mass. The molar mass of AlCl3 is the sum of the atomic masses of Al and Cl (Al: 26.98 g/mol, Cl: 35.45 g/mol).
Calculate the moles of AlCl3 by dividing the mass of AlCl3 (13.12 g) by its molar mass.
Calculate the molality of the solution by dividing the moles of AlCl3 by the mass of water in kilograms (615 g of water is 0.615 kg).
Use the boiling point elevation formula: ΔT_b = i * K_b * m, where ΔT_b is the boiling point elevation, i is the van't Hoff factor (which is 4 for AlCl3, as it dissociates into 4 ions: Al^3+ and 3 Cl^-), K_b is the ebullioscopic constant for water (0.512 °C kg/mol), and m is the molality.
Add the boiling point elevation (ΔT_b) to the normal boiling point of water (100°C) to find the new boiling point.
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