chem 1

• Objectives


  • Describe the effect of temperature and pressure on the solubility of a solid and gas
  • Describe the different colligative properties of solutions
• Solubility


  The maximum amount of solute that can dissolve in a given amount of solvent at a given temperature
• Factors affecting solubility


  • Nature of solute and solvent
  • Temperature
• "Like dissolves like"


  Solute and solvent must be similar in terms of polarity
• Ionic and polar solutes


  Soluble in polar solvents
• Nonpolar solutes


  Soluble in nonpolar solvents
• Particle size


  • Smaller particles will have higher solubility
  • Stirring the solutions also helps increase solubility of a solid solute
• For most solids dissolved in liquids

  Solubility increases with temperature
• Solubility of gas in liquids

  Has an inverse relationship with temperature
• Colligative properties


  Properties that depend only upon the number of solute particles (concentration), and NOT upon their identity
• Colligative properties


  • Vapor-pressure lowering
  • Freezing-point depression
  • Boiling-point elevation

  
• Vapor pressure


  The pressure exerted by a vapor that is in dynamic equilibrium with its liquid
• Solution with solute not easily vaporized

  Has lower vapor pressure than pure solvent
• Decrease in solution's vapor pressure

  Proportional to the number of particles the solute makes in solution
• Freezing-point depression


  The difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

  
• Presence of solute in water disrupts the formation of the orderly pattern of ice, requiring more kinetic energy to be withdrawn for the solution to solidify

  
• Magnitude of freezing-point depression is proportional to the number of solute particles dissolved in the solvent and does not depend upon their identity

  
• Boiling point


  The temperature at which the vapor pressure of the liquid phase equals atmospheric pressure
• Boiling-point elevation


  The difference in temperature between the boiling point of a solution and the boiling point of the pure solvent

  
• Magnitude of boiling-point elevation is proportional to the number of solute particles dissolved in the solvent