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• Solution


  Homogeneous mixture where a solute is dissolved in a solvent
• In Grade 6, you have learned about different mixtures and their characteristics
• Homogeneous mixtures are called solutions
• Solvent


  The component present in greater amount in a solution
• Solute


  The component present in smaller amount in a solution
• Types of solutions


  • Solid in liquid
  • Gas in liquid
  • Solid in solid
  • Gas in gas
  • Liquid in liquid
• Many commercial products are sold as solutions
• Properties of solutions


  • Uniform appearance and properties throughout
  • Solute particles are too small to be seen by the naked eye
  • Solute particles cannot be separated by filtration
• Identifying a saturated solution

  1. Add solute to solvent

  2. Stir to dissolve

  3. Keep adding solute until no more dissolves

  4. Excess solute remains undissolved
• The maximum amount of solute that will completely dissolve in a given volume of solvent is the solubility
• A saturated solution is one in which the maximum amount of solute has dissolved in the solvent
• In a saturated solution, excess undissolved solute is present
• Dissolving sugar in water

  1. Add a small portion at a time

  2. Stir the solution to dissolve the sugar

  3. Add 1/2 teaspoon of sugar

  4. Stir the solution

  5. Continue adding 1/2 teaspoon of sugar until it no longer dissolves
• Saturated solution


  The solution that contains the maximum amount of solute dissolved by a given amount of solvent
• Unsaturated solution


  A solution that contains less solute than the maximum amount it can dissolve at a given temperature
• The presence of an excess solid which can no longer dissolve is evidence that the solution is saturated
• Solubility


  The maximum amount of solute that can dissolve in a given amount of solvent at a certain temperature
• A more measurable way to find out the solubility of a solute is to determine the maximum amount that can be dissolved in 100 g of solvent at a specific temperature
• Solubility data


  • Figure 2 shows the solubility of table salt at 25°C
• Concentration


  The relative amounts of solute and solvent in a given volume of solution
• Concentrated solution


  A solution with a large amount of dissolved solute for a certain volume of solvent
• Dilute solution


  A solution with a small amount of dissolved solute in comparison to the amount of solvent
• Concentration can be expressed as percent by volume or percent by mass
• Concentration expressions


  • 70% ethyl or isopropyl alcohol
  • 5% acidity in vinegar
  • 3% hydrogen peroxide in agua oxinada
  • Karat for solid solutions like gold jewelry
• Calculating concentration


  1. Sample problem 1: Calculating amount of ethyl alcohol in 50 mL of rubbing alcohol

  2. Sample problem 2: Calculating amount of copper in a 1 peso coin
• Factors affecting dissolving rate

  • Stirring
  • Particle size
  • Temperature
  • Nature of solute
• Investigating effect of particle size

  1. Write hypothesis

  2. Identify variables

  3. Identify dependent and independent variables

  4. List materials

  5. Record observations

  6. Draw conclusion

  7. Explain results
• Investigating effect of temperature

  1. Write hypothesis

  2. Identify variables

  3. Identify dependent and independent variables

  4. List materials

  5. Record observations

  6. Draw conclusion

  7. Explain results
• Investigating effect of solute type

  1. Write hypothesis

  2. Identify variables

  3. Identify dependent and independent variables

  4. List materials

  5. Record observations

  6. Draw conclusion

  7. Explain results
• The type or nature of the solute will affect how fast it dissolves in water
• Increasing temperature can make a solid dissolve faster or slower in water, or have no effect
• Many things around you are mixtures. Some are solid like brass and rocks, or liquid like seawater and fruit juices, or gas like air. Mixtures contain two or more components. These components may vary in size. The variation in size may tell whether a mixture is homogeneous or heterogeneous.
• Homogeneous mixture


  A mixture with a uniform composition, making the appearance of the mixture the same all throughout. The components are difficult to distinguish by the unaided eye.
• Separating components of a mixture

  1. Distillation

  2. Evaporation
• Distillation and evaporation will help "see" the two major components of seawater — water and salt.
• Seawater is a solution of many different solids, including table salt, in water. Since the solids are dissolved in water, decantation or filtration will not work in separating water from the dissolved solids. Other separation techniques are needed.
• Distilled water is considered a substance.
• Substance


  A pure chemical compound or element that cannot be separated into simpler substances by physical means.
• Boiling a substance


  Temperature remains constant during boiling
• Boiling a mixture


  Temperature varies during boiling