Solutions

Homogeneous Solutions

Vocabulary

• Aqueous solution: water that contains dissolved substances

• Solute: substance being dissolved

• Solvent: dissolving agent-usually present in larger amount

• Solution: homogeneous mixture

The Solution Process1. Solvation: The process by which the solute ions break away from the crystal and become surrounded by solvent molecules as the ionic crystal dissolves. Ionic Solid

NaCl(s) Na+(aq) + Cl-(aq)

CuCl2(s) Cu2+(aq) + 2 Cl-(aq)

CaSO4(s) Ca2+ (aq) + SO4

2- (aq)

BaBr2(s) Ba 2+ (aq) + 2Br- (aq)

K2SO4(s) 2K+ (aq) + SO42-(aq)

http://www.elmhurst.edu/~chm/vchembook/171solublesalts.html

b) Molecular Solids (Like Dissolves Like)

C6H12O6(s) → C6H12O6(aq)

-Polar dissolves Polar

-Non-polar dissolves Non-polar

Electrolyte: A substance that conducts in an aqueous solution

Non-electrolyte: A substance that does not conduct

Strong electrolyte: a substance that conducts well

Weak electrolyte: a substance that conducts poorly

Solubility CurvesVocabulary:

• Saturated: solvent is holding the maximum amount of solute = equilibrium • Unsaturated: solvent is holding less than the maximum amount of solute

• Supersaturated: solvent contains more solute that it should = unstable • Solubility: grams of solute per 100g solvent that will dissolve in solvent

• Soluble: solute readily dissolves • Insoluble: solute does not dissolve appreciably • Solubility Curve: graph of solubility versus temperature • Miscible: capable of dissolving to form a homogeneous solution

• Immiscible: incapable of dissolving

• http://www.elmhurst.edu/~chm/vchembook/106Amixture.html

Solubility Relationships

1. Solubility of an ionic solid

http://www.ucl.ac.uk/news/uclviews/0803/salt500

2. Solubility of a gas

Demonstration: Supersaturated Solution

1. What was added to the test tube?Sodium ThiosulfateNa2S2O3.5H2O

2. How was the solubility of the solution increased? by heating the solution

3. What happened when a crystal was added to the saturated solution after cooling? What type of solution was created?

• The solution could not hold that much dissolved solid and it precipitated out

• Supersaturated Solution