SC2 - Methods of Separating and Purifying substances

  • Created by: lx1234
  • Created on: 13-04-18 15:34
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  • Elements
    • SC2
      • Compounds
        • A substance consisting of atoms of two or more different elements, chemically joined together
        • E.g Water is a compound consists of hydrogen atoms and oxygen atoms
      • Monatomic: A single atom of an element
      • Diatomic: Two atoms of the same element bonded.
      • Pure Substances
        • Only contains one element or compound.
        • Pure hydrogen contains only hydrogen molecules
        • Pure water contains only water molecules
      • Mixtures
        • impure substances
        • They contain different elements/ compounds
        • Components of a mixture are not chemically joined together
      • Distillation
        • Simple Distillation
          • Used to separate a solvent from a sollution
          • Set up: Flask, connect to condenser, beaker at the end, cork to stop vapour leaving.
          • Solution is heated, solvent boils, solvent vapour passes into the condenser, vapour is cooled and condensed back into liquid state
          • Works as solute in the solution has a much higher boiling point than solvent.
        • Fractional Distilation
          • Used to separate a liquid from a mixture of miscible liquids (liquids that mix completely)
          • Set up: Fractionating column, beaker, condenser, thermometer, cork, beaker.
          • Mixture is heated, mixture boils, hot vapour rises up fractionating column, vapour condenses when it hits cool surface of the colum and drips back, the fraction with the lowest boilinf point reaches the top of the column first, iots vapour passes into condenser.
          • hot at the top, cold at the bottom
      • Filtration
        • Used to separate an insoluble substance from a liquid or a solution
        • Done to purify a liquid to a solution by removing solid impurities
        • Done to separate the solid you want from liquid mixed with it.
        • Set up funnel, filter paper, beaker
        • Filter paper allows water molecules and dissolved substances through, wont allow insoluble solid particles
      • Solubility: Mass of solute dissolved in a given volume of a solvent at a given temperature
      • Decanting: Pouring the liquid away carefully so the solid stays behind.
      • Chromatography
        • Used to separate mixtures of soluble substances
        • Stationary Phase: A substance that does not move
        • Mobile Phase: A substance that moves through stationary phase
        • Each soluable substance in the mixture forms bonds with the phases, substances form stronger attractive forces with the stationary phase stay near the bottom, substances that form stronger attractive forces with the mobile phase move towards the top
        • Used to identify a substance by comparing it with known substances
        • Rf=Distance travelled by spot/Distance travelled by solvent.
    • Hydrogen is an element because its atoms all have one proton in their nucleus
    • A substance that consists only of atoms with the same atomic number.
  • Compounds
    • A substance consisting of atoms of two or more different elements, chemically joined together
    • E.g Water is a compound consists of hydrogen atoms and oxygen atoms
  • Crystallisation
    • produces solid crystals from a solution
    • SC2
      • Monatomic: A single atom of an element
      • Diatomic: Two atoms of the same element bonded.
      • Pure Substances
        • Only contains one element or compound.
        • Pure hydrogen contains only hydrogen molecules
        • Pure water contains only water molecules
      • Mixtures
        • impure substances
        • They contain different elements/ compounds
        • Components of a mixture are not chemically joined together
      • Distillation
        • Simple Distillation
          • Used to separate a solvent from a sollution
          • Set up: Flask, connect to condenser, beaker at the end, cork to stop vapour leaving.
          • Solution is heated, solvent boils, solvent vapour passes into the condenser, vapour is cooled and condensed back into liquid state
          • Works as solute in the solution has a much higher boiling point than solvent.
        • Fractional Distilation
          • Used to separate a liquid from a mixture of miscible liquids (liquids that mix completely)
          • Set up: Fractionating column, beaker, condenser, thermometer, cork, beaker.
          • Mixture is heated, mixture boils, hot vapour rises up fractionating column, vapour condenses when it hits cool surface of the colum and drips back, the fraction with the lowest boilinf point reaches the top of the column first, iots vapour passes into condenser.
          • hot at the top, cold at the bottom
      • Filtration
        • Used to separate an insoluble substance from a liquid or a solution
        • Done to purify a liquid to a solution by removing solid impurities
        • Done to separate the solid you want from liquid mixed with it.
        • Set up funnel, filter paper, beaker
        • Filter paper allows water molecules and dissolved substances through, wont allow insoluble solid particles
      • Solubility: Mass of solute dissolved in a given volume of a solvent at a given temperature
      • Decanting: Pouring the liquid away carefully so the solid stays behind.
      • Chromatography
        • Used to separate mixtures of soluble substances
        • Stationary Phase: A substance that does not move
        • Mobile Phase: A substance that moves through stationary phase
        • Each soluable substance in the mixture forms bonds with the phases, substances form stronger attractive forces with the stationary phase stay near the bottom, substances that form stronger attractive forces with the mobile phase move towards the top
        • Used to identify a substance by comparing it with known substances
        • Rf=Distance travelled by spot/Distance travelled by solvent.
    • Solution heated to remove enough solvent to produce saturated solution, solution allowed to cool, crystals form, crystals separated from liquid and dried
    • Works because solubility of solute decreases as the saturated solution cools, crystals form from escess solute
  • Drinking Water
    • 1. Sedimentation: large insoluble particles sink to bottom of a tank
      • 2. Filtration: Small insoluble particles are removed by filtering through beds of sand
        • 3. Chlorination: Chlorine gas is bubbled from the water to kill microbes
    • 2. Filtration: Small insoluble particles are removed by filtering through beds of sand
      • 3. Chlorination: Chlorine gas is bubbled from the water to kill microbes
    • Potable drinking water must have: Low levels of contaminating substances, low levels of microbes
    • Water from lakes, oceans and reservoirs, contain objects e.g leaves, insoluable solids, microbes.
    • tap water is safe but not pure
    • Sea water is made potable by filtering it, boiling it, condensing it to form distilled water
    • simple distillation of sea water uses plentiful raw material, produces pure water, kills microbes, needs energy

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