Open Question
What is the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 104.0 °C?
14. Solutions
Boiling Point Elevation
Multiple Choice
A glucose solution contains 55.8 g of glucose (C6H12O6) in 455 g of water. Determine the boiling point of the solution. The boiling point elevation constant (Kb) for water is 0.512 °C/m. What is the boiling point of the solution?
A
99.85 °C
B
101.02 °C
C
100.39 °C
D
100.12 °C
Verified step by step guidance1
Calculate the molar mass of glucose (C6H12O6) using the atomic masses: Carbon (C) = 12.01 g/mol, Hydrogen (H) = 1.01 g/mol, Oxygen (O) = 16.00 g/mol. Use the formula: Molar mass = (6 * 12.01) + (12 * 1.01) + (6 * 16.00).
Determine the number of moles of glucose by dividing the mass of glucose by its molar mass. Use the formula: Moles of glucose = \( \frac{55.8 \text{ g}}{\text{Molar mass of glucose}} \).
Calculate the molality of the solution, which is the moles of solute per kilogram of solvent. Use the formula: Molality (m) = \( \frac{\text{Moles of glucose}}{0.455 \text{ kg of water}} \).
Use the boiling point elevation formula to find the change in boiling point: \( \Delta T_b = K_b \times m \), where \( K_b \) is the boiling point elevation constant (0.512 °C/m) and \( m \) is the molality.
Add the boiling point elevation (\( \Delta T_b \)) to the normal boiling point of water (100 °C) to find the boiling point of the solution: Boiling point of solution = 100 °C + \( \Delta T_b \).
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