IB Chem Unit 6 Pages 1-4

Solution

• A uniform mixture (homogeneous

  • Solute + Solvent combined

Solute

• Substance that is being dissolved

• Usually the smallest amount

Solvent

• Substance that is doing the dissolving

• Usually the largest ammount

Solubility

• The amount of solute that can be dissolved in a given amount of solvent at a certain temperature

• Physical property

• Usually expressed in g/L

Soluble & Insoluable

• Soluble

  • Can be dissolved in a specific solvent

    • NaCl is soluble in water

• Insoluble

  • Can not be dissolved in a specific solvent

    • NaCl is insoluble in oil

Unsaturated

Solution can still dissolve more solutes

Saturated

Solution has reached its max and can’t dissolve anymore

Supersaturated

Solution has more solutes than the maximum amount that it can dissolve

Miscible

• Two liquids that can be mixed together

  • Water + ethanol

Immiscible

• Two liquids that cannot be mixed together

  • Water + oil

Why Things Dissolve

• Depends on attraction within the solute and solvent and between the solute and solvent

• Likes dissolve likes

Nonpolar Solutes

• Soluble in nonpolar solvents

• Insoluble in polar solvents

Polar and Ionic Solutes

• Soluble in polar solvents

• Insoluble in nonpolar solvents

Factors Affecting Solubility

• For solids dissolved in liquids

  • Solubility increases as temperature increases

• For gases dissolved in liquids

  • Solubility decreases as temperature increases

  • Solubility increases as pressure increases

Factors Affecting Solubility (Continued)

• Stirring

  • Increases the rate of solubility

• Particle Size

  • The smaller the particles, the faster it will dissolve

X & Y Axis for Solubility curves

• X- Axis

  • Temperature (^oC)

• Y-Axis

  • Solubility (g of solute per 100 g of H₂O)

    

How to read solubility curves

• The line represents a saturated solution

  • On the line = saturated

  • Below the line = unsaturated

  • Above the line = supersaturated

Dissociation

• Separation of ions

• Ionic compounds and acids dissociate to some extent in solution

• Covalent compounds do not dissociate

How do ionic solutions dissolve

• When an ionic compound dissolves in water, water molecules separate, surround and pull the ions into the liquid.