Analysis

• Pure substance

  Contains a single element or compound

  Melt and boil at specific temperatures
• Impure substances

  Contain more than one type of element or compound

  Melt and boil at a range of temps
• Formulations

  Example of mixtures

  Specific purposes
• How can we separate mixtures (4)

  1. Filtration
  2. Crystallisation
  3. Simple distillation
  4. Fractional distillation
• Filtration

  Separates insoluble solids from a liquid
• Crystallisation

  Evaporates a solvent (liquid) leaving the solute (solid)
• Simple distillation

  Separates the solvent from a solution

  Solvent has to have a lower boiling point than the solute
• Fractional distillation

  Separates 2 or more substances from a liquid mixture
• Chromatography

  A method to separate diff components from a mixture
• What is the r(small f) value

  A ratio of how far up the paper a certain spot moves compared to how far the solvent has travelled
• How to calculate r(small f) value

  Distance moved by substance / distance moved by solvent
• Stationary phase of chromatography - Paper
• Mobile phase of chromatography - Solvent
• Solvent front - Top of where solvent travels
• Chromatography steps

  1. Draw a pencil line 1cm above bottom of paper
  2. Place dots of mixture along the pencil line, label with pencil
  3. Place the bottom of the paper into a solvent
  4. Let the solvent travel up the paper
  5. Calculate the r(small f) value
• Hydrogen test

  Test: hold a lit splint near the gas

  Result if present: hear a squeaky pop
• Oxygen test

  Test: hold a glowing splint near the gas

  Result if present: splint re-lights
• Carbon dioxide test


  Test: bubble through limewater

  Result if present: limewater turns milky
• Chlorine test

  Test: hold a piece of damp litmus near the gas

  Result: bleaches the litmus white