CHMA10H3 Lecture Notes - Lecture 19: Intermolecular Force, Solution Process, JoulePremium

3 pages129 viewsFall 2018

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Marco Zimmer-De Iuliis, Xiaoan Zhang, Scott Ballantyne

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CHMA10 Lecture 16: Understanding Intermolecular Forces and Solution Formation
- Chapter 12
- Solutions: homogenous mixtures
o Eg: when mixing salt and water, salt will disappear
The solute in this case is the salt
The solvent is water
o Solute: solution component that changes state
o Solvent: solution component that keeps its state
o In order for a solute to mix with a solvent to form a solution, two sets of forces
must be overcome
1: All of the solute-solute attractive forces holding the solute together
2: Some of the solvent-solvent attractive forces
Both sets of forces are endothermic
Some of the energy required to break them comes from making
new solute-solvent interactions
o The forming of new bonds is an exothermic process
- Intermolecular forces and the solution process
o There are 2 things that drive solution formation
1: Entropy: Nature’s tendency towards mixing
2: the types of intermolecular forces
o There are 3 scenarios that can occur when making a solution
1: the solute-solvent attraction is stronger than the solute-solute and
solvent-solvent attractions
The energy released by the formation of bonds between the
solute and solvent is greater than the energy needed to break
apart the solute and solvent bonds
It is likely that a solution will form in this scenario
o Entropy favors solution formation here
2: the solute-solvent attraction is equal to the solute-solute and solvent-
solvent attractions
The solution will still likely form
3: the solute-solvent attractions is weaker than the solute-solute and
solvent-solvent attractions
The solute-solvent attraction requires more energy than is
released when they combine
The solution will only form here if the energy difference between
the breaking and forming of bonds is small
o Within 2-3 kJ
- Energetics of solution formation
o As previously mentioned, to form a solution you must:
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