Unit 3 Intermolecular Forces and Properties Topic 3

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Unit 3 Intermolecular Forces and Properties Topic 3. 10 Solubility Text Reference Ch 13,

Unit 3 Intermolecular Forces and Properties Topic 3. 10 Solubility Text Reference Ch 13, section 13. 3

 • Understanding: Interactions between intermolecular forces influence the solubility and separation of mixtures.

• Understanding: Interactions between intermolecular forces influence the solubility and separation of mixtures. • Learning Objective: Explain the relationship between the solubility of ionic and molecular compounds in aqueous and nonaqueous solvents, and the intermolecular interactions between particles. • Essential Knowledge: Substances with similar intermolecular interactions tend to be miscible or soluble in one another. 2

Solute-Solvent Interactions • Chemists use the axiom “like dissolves like”: -- Polar substances tend

Solute-Solvent Interactions • Chemists use the axiom “like dissolves like”: -- Polar substances tend to dissolve in polar solvents. -- Nonpolar substances tend to dissolve in nonpolar solvents. • The stronger the solute–solvent interaction, the greater the solubility of a solute in that solvent. 3

 • The gases in the table exhibit only dispersion force in water which

• The gases in the table exhibit only dispersion force in water which is very polar. The larger the gas particle, the more soluble it will be in water. 4

 • Alcohol solubility is affected by the length of the nonpolar part of

• Alcohol solubility is affected by the length of the nonpolar part of the molecules. The longer the nonpolar part the less soluble the alcohols are in water and the more soluble they are in a nonpolar solvent. 5

 • Polar organic molecules dissolve in water better than nonpolar organic molecules. 6

• Polar organic molecules dissolve in water better than nonpolar organic molecules. 6

 • Hydrogen bonding increases solubility, since C–C and C–H bonds are not polar

• Hydrogen bonding increases solubility, since C–C and C–H bonds are not polar or only very slightly polar. 7

 • Solubility and biological importance Ø Fat-soluble vitamins (like vitamin A) are nonpolar;

• Solubility and biological importance Ø Fat-soluble vitamins (like vitamin A) are nonpolar; they are readily stored in fatty tissue in the body. Ø Water-soluble vitamins (like vitamin C) need to be included in the daily diet. 8