solutions

Definition of Solution

• Mixture of two or more substances

• Homogeneous mixture (thoroughly mixed)

Terms Related to Solutions

• Solute

• Substance being dissolved

• Example: Sugar in water

• Solvent

• Substance in which solute is dissolved

• Example: Water

Types of Solutions

• Aqueous Solutions

• Substances dissolved in water

• Solid-Liquid

• Example: Sugar or salt in water

• Gas-Liquid

• Example: CO2 in carbonated drinks

• Liquid-Liquid

• Example: Alcohol in water

• Gas-Gas

• Example: Air (mixture of gases)

• Solid-Solid

• Example: Brass (copper and zinc)

Dissolving Process

• Enthalpy Considerations

1. Endothermic Processes

   • Energy needed to separate solute (overcoming intermolecular forces)

   • Energy needed to separate solvent

2. Exothermic Process

   • Energy released during mixing, forming new intermolecular forces

• Examples of Enthalpy

• Sugar and water: typical exothermic dissolution

• Cold packs: endothermic process

Solubility Factors

• Like Dissolves Like

• Polar solute in polar solvent (e.g., sugar in water)

• Non-polar solute in non-polar solvent (e.g., oil in gasoline)

• Non-polar solute in polar solvent: usually doesn’t dissolve (e.g., oil in water)