Electrolysis

• Electrolytes are ionic compounds that are:

  • in the molten state (heated so they become liquids), or
  • dissolved in water
• The electrodes used in electrolysis must be made from metals that do not react with the substances being separated.
• When current flows into the electrolyte, it causes chemical reactions at the electrodes.
• In an electrochemical cell, electrons flow from the negative terminal to the positive terminal through the external circuit.
• In an electrochemical cell, electrons flow from the negative to positive terminal through the external circuit.
• At the cathode, metal atoms gain electrons to form negatively charged ions.
• At the negative electrode, metal atoms lose electrons to form positive ions which move towards the positive electrode.
• At the positive electrode, hydrogen gas is produced by the reaction between hydrogen ions and electrons.
• At the anode, metal atoms lose electrons to form positively charged ions.
• In an acid solution, hydrochloric acid reacts with zinc to produce hydrogen gas and zinc chloride.
• During electrolysis, the products formed depend on which elements have been added as electrodes.
• If the electrode is made of carbon, then only non-metal atoms will be deposited onto the electrode.
• The overall equation shows that water molecules are broken down into oxygen and hydrogen gases during electrolysis.
• Electrolytes are ionic compounds that dissolve in water or other solvents to produce positively and negatively charged particles called ions.
• Ions can carry electrical charge because they have lost or gained one or more electrons.