Chemical changes

• How to make salts/crystals


  •measure e.g. 40cm³ of sulfric acid

  •pour into beaker

  •heat beaker for 30 seconds

  •add excess of e.g. copper oxide

  •stir

  • filter out excess

  •evaporate water out by pouring solution into evaporating basin and heat
• Electrolysis required practical

  • fill beaker around 15cm³ of chemical

  • submerge electrodes in liquid

  • connect power pack with 3 volts

  • connect a wire from power pack to anode and one to cathode

  • leave for 5 minutes whilst watching for reaction

  • hold litmus paper above anode to see if it bleaches
• what are the salt names to these acids

  hydrochloric acid = chloride

  sulfuric acid = sulfate

  nitric acid = nitrate
• define neutralisation

  • acids are neutralised by bases and alkalis
• what happens to metal and oxygen

  react to form metal oxides
• define oxidation

  • loss of electrons but gain of oxygen
• define reduction

  gain of electrons but loss of oxygen
• group 1 reacting with water and reacting with acid

  • get more vigarous as you go down group - water
  • get more vigarous as you go down group - acid
• group 2 reacting with water and acid

  • no reaction - water
  • fizzing and temperature increase - acid
• zinc, iron, copper reacting with water and acid

  • no reaction - water
  • zinc and iron react slowly - acid
  • copper no reaction - acid
• using carbon for extraction

  metals less reactive than carbon can be extracted using carbon
• reaction with acid

  • redox reaction as metal donates electrons to hydrogen displacing it
• what is produced at the negative electrode

  metal produced if less reactive than hydrogen
• what is produced at the positive electrode

  • oxygen is formed unless its a halogen element
• which ion is positive so it attract negative ions

  cation ion at cathode
• which ion is negative so it attracts positive ions

  anions are negative ions and anode
• define electrolysis

  • splitting of ions in water using electricity
• define strong acid

  • completely ionised in aqueous solution
• define weak acid

  • only partially ionised in aqueous solution e.g. citric acid
• hydrogen ion in concentration

  as pH becomes more acidic hydrogen ion increase by factor of 10
• define soluble salts

  • made with reacting acids with solid insoluble solution
• where are the electrons in cathode half equation

  left side
• where are the electrons on the anode half equation

  right side