Chemical changes

• What is electrolysis?

  Electrolysis is the process that uses electricity to split an ionic compound
• What does the compound have to be?

  Aqueous or molten
• Positive Ions

  Attracted to negative cathode
• Negative ions

  Attracted to positive anode
• Metals

  Form positive ions
• Non-metals

  Form negative ions
• What is a molten compound?

  Compound that’s melted
• What is an aqueous solution?

  A solution dissolved in water
• What happens at cathode in aqueous solution?

  The least reactive is discharged or hydrogen
• What happens at anode in aqueous solution?

  The hallogen is discharged or else oxygen is formed from hydroxide ions
• What else happens in an aqueous solution?

  The remaining ions may form another product
• Reduction

  At the cathode
• Oxidation 


  At anode
• What is reduction?

  The loss of oxygen, the gain of electrons
• What is oxidation?

  The gain of oxygen, the loss of electrons
• Advantages

  Product is very pure

  Highly efficient

  Useful for very reactive metals
• Disadvantages

  Time consuming

  Requires a lot of energy

  Expensive cost of electricity

  Cost of equipment
• Whats the hydrogen 1/2 equation?

  $2H^+$$+$$2e^- → H2$
• What’s the 1/2 equation of hydroxide in aqueous solution?

  $40H^- → 02 +$$2H20 +$$4e^-$
• Metal displacement reactions are chemical reactions where one metal replaces another metal in its compound
• Metals less reactive than carbon can be extracted by displacement using carbon
• The reactivity series places elements by how reactive they are

  Reactive at top

  Least reactive at bottom
• When reacting what do metals form?

  Positive ions
• What do non-metals form?

  Negative ions
• Reactivity is based around how easily it loses/gains electrons to form a full outer shell
• What groups are most reactive elements in?

  Group 1 and 7
• What happens to reactivity going down group 1?

  It increases
• What happens to reactivity going down group 7?

  It decreases
• Why reactivity increases in group 1?

  The atom increases in size, so there are more electron shells which cause shielding and the atomic radii increases therefore electrostatic forces of attraction are weaker and the outer electron is lost easier, forming a positive ion.
• Why reactivity decreases down group 7?

  Going down the atoms are larger therefore there are more electron shells which causes shielding, also the atomic radii increases so the electrostatic forces of attractions are weaker and it's harder to gain the outer electron required for group 7 elements to become stable
• Neutralisation

  Acid + Alkali → Salt + Water
• Metal

  Metal + Acid → Salt + Hydrogen
• Metal oxide

  Metal oxide + Acid → Metal salt + Water
• Metal carbonate

  Metal carbonate + Acid → Metal salt + Carbon dioxide + Water
• Displacement

  More reactive metal is able to displace a less reactive metal to form a new compound
• What can neutralise an acid?

  Metals

  Metal oxides

  Metal hydroxides

  Metal carbonates
• All acids contain hydrogen ions
• All alkalis contain hydroxides
• All alkalis are bases BUT not all bases are alkalis
• Ph 1-6

  Acids