GCSE Chemistry - Electrolysis

• What is electrolysis?

  passing an electric current through an ionic substance that's molten or in a solution and breaks it down into new substances
• What is electrolysis used for?

  To make new substances
• What is an electrolyte?

  a liquid that conducts electricity
• How are electrolytes made?

  by melting or dissolving ionic compounds
• Which part of an electrolyte conducts electricity?

  The free electrons
• What is the a positive electrode called?

  Anode
• What is a negative electrode called?

  Cathode
• What are electrodes made from and why?

  Unreactive metal so they don't take part in the reaction
• How do ions become atoms or molecules?

  By losing or gaining electrons
• How does an electrolysis circuit become complete?

  A flow of electrons taken from anodes to cathodes
• How do you measure the conductivity of an electrolyte?

  With a conductivity probe
• In molten ionic compounds there is only ___________

  one source of ions
• Why can molten ionic compounds be electrolysed?

  Because ions can move freely
• In the electrolysis of molten lead bromide what is the half equation for the Pb2+ ions?

  Pb2 + 2e --> Pb
• In the electrolysis of molten lead bromide what is the half equation for the Br- ions?

  2Br- -->Br2 + 2e
• In the electrolysis of molten lead bromide what happens to the lead ions?

  They are attracted to the cathode (because they are positive) and gain two electrons to become lead atoms and sink to the bottom of the beaker
• In the electrolysis of molten lead bromide what happens to the bromide ions?

  They are attracted to the anode (because they are negative) and lose two electrons to become bromine molecules. brown bromine gas forms at the top of the anode.
• What is an electric current?

  The flow of electrons or ions
• What is a covalent bond?

  a shared pair of electrons
• Why can't covalent compounds conduct electricity?

  Because a covalent compound leaves no spare electrons in the outer shell so there are no free electrons to carry the current
• What is an ionic bond?

  when an atom loses or gains electrons to form charged particles
• Why can ionic compounds only conduct electricity when molten or in a solution

  an ionic compound in solid state forms a lattice so the ions aren't free to move around. when they are dissolved or melted the ions separate and are free to carry electrical currents