Ch.12 - SolutionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 107.1 oC.

Solution: Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 107.1 oC.

Problem

Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 107.1 oC.

Solution

We’re being asked to calculate the mass percent of ethylene glycol (C2H6O2) solution to have a boiling point of 107.1 oC.


Recall that the boiling point of a solution is higher than that of the pure solvent and the change in boiling point (ΔT­b) is given by:


Tb = Tb, solution - Tb, pure solvent 


The change in boiling point is also related to the molality of the solution:


Tb = iKbm


where: 

i = van’t Hoff factor

m = molality of the solution (in m or mol/kg)

Kb = boiling point elevation constant (in ˚C/m)


Recall that the molality of a solution is given by:


Molality (m) = moles of soluteKilograms of solvent


We go through the following steps to solve:

Step 1. Calculate the molality

Step 2. Calculate the mass of solute and solvent

Step 3. Calculate the mass percent


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