Definitions

• What do acids produce in aqueous solutions?


  Hydrogen ions (H+)
• What is the pH range of acids?


  0 - 6
• What do alkalis produce in aqueous solutions?


  Hydroxide ions (OH-)
• What is the pH range of alkalis?


  7 - 14
• What is crystallisation used for?


  To produce solid crystals from a solution by evaporating the solvent
• What is a displacement reaction?


  A reaction where a more reactive element displaces a less reactive element from its compound
• What is electrolysis?


  The splitting up of an ionic compound using electricity
• What is an electrolyte?


  A solution containing free ions from a molten or dissolved ionic substance
• What is the purpose of extraction techniques?


  To separate a desired substance when it is mixed with others
• What is filtration used for?


  To separate solids from liquids
• What happens at the negative electrode (cathode) during electrolysis?


  Hydrogen is produced if the metal in the electrolyte is more reactive than hydrogen
• What is neutralisation?


  The reaction when an acid and a base react to form water and a salt
• What is oxidation?


  A reaction involving the gain of oxygen
• What does the pH scale measure?


  The acidity or alkalinity of a solution
• What is produced at the positive electrode (anode) during electrolysis?


  Oxygen is produced unless the solution contains halide ions
• What is a redox reaction?


  A reaction in which both oxidation and reduction occur simultaneously
• What is reduction?


  A reaction involving the loss of oxygen
• How can metals less reactive than carbon be extracted?


  By reduction with carbon
• What is a strong acid?


  A strong acid is completely ionised in aqueous solution
• Name three examples of strong acids.


  Hydrochloric, nitric, and sulfuric acids
• What is the reactivity series?


  A list of metals arranged in order of their reactivity
• What is titration used for?


  To determine the concentration of an unknown solution
• What is a universal indicator?


  A mixture of dyes that changes colour gradually over a range of pH
• What is a weak acid?


  A weak acid is only partially ionised in aqueous solution
• Name three examples of weak acids.


  Ethanoic, citric, and carbonic acids