Separating mixtures

Cards (31)

  • compound

    substances that form when two or more elements react and their atoms chemically combine in a fixed ratio by mass.
  • mixture

    a physical combination of two or more substances that aren't chemically joined.
  • substances in a mixture can be both elements or compounds, and they keep their individual properties.
    • Compounds can only be separated using CHEMICAL REACTIONS.
    • Mixtures can be separate using PHYSICAL METHODS.
  • Examples of Physical Separation Techniques:
    • FILTRATION
    • EVAPORATION
    • CRYSTALLISATION
    • SIMPLE DISTILLATION
    • FRACTIONAL DISTILLATION
    • CHROMATOGRAPHY
  • Solute

    a solid that dissolves
  • solvent 

    a liquid the does the dissolving
  • solution

    formed when a solute completely dissolves in a solvent.
  • soluble

    If a solute dissolves in a solvent then its soluble
  • insoluble

    If a solute doesn't dissolves in a solvent then its insoluble
  • Filtration

    A method used to separate an insoluble solid from a liquid, useful for removing solid impurities from a reaction, mixture or product.
  • Filtration involves pouring the mixture through a filter paper, where the solid is trapped and the liquid passes through.
    • SOLUBLE SOLIDS, like salt, can be dissolved in a SOLVENT and then recovered by EVAPORATION or CRYSTALLISATION.
  • Evaporation:
    1. Pour the solution into an evaporating dish and heat it.
    2. As the solvent evaporates, the solution becomes concentrated and dry crystals form.
    • This method is used when the substance does not compose upon heating.
  • Crystallisation:
    1. Start with solution in an evaporating dish
    2. Heat gently until crystals form, indicating that the solution of more crystals
    3. Allow the solution to cool, which causes the formation of more crystals.
    4. Filter out the crystals and leave them to dry in a warm place.
  • SIMPLE DISTILLATION

    a process to separate a LIQUID from a solution, used when the liquids have different BOILING POINTS.
  • Simple Distillation:
    1. The solution is heated to the temperature of the lowest boiling point, causing the component with the lower boiling point to evaporate.
    2. The vapour is then cooled in a condenser and collected as a liquid, leaving the component with the higher boiling point behind.
    • This method is ideal for purifying water from seawater or separating a liquid from a reaction mixture.
  • FRACTIONAL DISTILLATION 

    Used when you have a mixture of MORE THAN TWO liquids that have different boiling points.
  • Fractional distillation involves using a FRACTIONATING COLUMN with glass rods in it to allow substances with different boiling points to separate effectively. Creates a TEMPERATURE GRADIENT where the temperature is HIGH at the BOTTOM and LOW at the TOP.
  • Fractional Distillation:
    1. As the vapour of the mixture rises, the temperature cools down which causes the component with higher boiling points to condense and fall back into the flask
    2. The component with the lowest boiling point will rise and condense into liquid and get collect in the beaker
    • Process is repeated, raising the temperature gradually collecting other liquids at different boiling points
  • Chromatography

    A method used to separate and analyse the components of a mixture.
  • In Paper chromatography, substances move at different rates, allowing them to be separated based on their solubility, used to separate out dyes in an ink.
  • How to Perform Paper Chromatography:
    1. Draw a line near the bottom of the filter paper with a pencil
    2. Place a spot of the substance to be separated on the line.
    3. Use water and Ensure the spot does not touch the solvent when you place the filter paper in the beaker.
    4. The solvent will move up the paper, taking the substances with it.
    5. Different substances in the mixture will travel at different speeds, resulting in separate spots.
    6. Once the solvent has nearly reached the top, remove the paper and let it dry to see the CHROMATOGRAM.
  • Describe what happens during distillation:
    water boils then water vapour cools in delivery tube distilled water is collected in the tube.
  • The salty water in step 4 still contained very small grains of sand.
    Suggest one improvement to step 4 to remove all the sand.
    filter
  • Evaporation at A
    Condensation at B
  • what is the reading on the thermometer during the process?
    100'C
  • Sand doesn't dissolves in water. A student separates a mixture of sand and water by filtration.
    Draw a diagram of the apparatus the student could use.
    You Should label:
    • Where the sand is collected
    • where the water is collected.
    A) filter paper
    B) funnel
    C) sand
    D) conical flask
    E) water
  • Suggest what would happen to the temperature of the water as the water flows through the condenser.
    increases
  • Describe how to obtain sodium chloride crystals from sodium chloride solution by crystallisation.
    Heat the solution to evaporate some of the water, then leave the solution to cool.
  • To remove salt from sea water use....
    Crystallisation