ACIDS - C1 Topic 3

ACIDS - C1 Topic 3

1. pH Neutral

   • Alkalis
     • 8-14
     • Red litmus paper turns purple under alkali conditions
   • Acids
     • 0-6
     • Blue litmus paper turns red under acidic conditions
   • 7

2. Neutralisation reaction

   • acid + base -> salt + water
     • makes salts, which has it's uses...
       • Fertilisers - e.g. ammonium nitrate, ammonium phonate
       • Fireworks and colouring agents
     • Some bases are soluble; when dissolved in water they become alkalis - which are soluble
   • Indigestion
     • HCL in the stomach kills bacteria in the food and creates an acidic environment for the enzymes.
       • Indigestion occurs when there's too much HCl in the stomach.
         • Tablets containing bases such as calcium carbonate neutralise the excess acid.

3. Reactions of acids

   • Metal oxides and metal hydroxides are bases -> they can neutralise acids to form a salt and water
     • acid + metal oxide -> salt + water
     • acid + metal hydroxide -> salt + water
     • The combination of metal and acid decides the salt
       • hydrochloric acid + copper oxide -> copper chloride + water
         • sulphuric acid + zinc oxide -> zinc sulfate + water
           • nitric acid + magnesium oxide -> magnesium nitrate + water
   • Metal carbonates (bubbles from reaction)
     • acid + metal carbonate -> salt + water + CO2
     • LBH <3
       • Hydrochloric acid + sodium carbonate -> sodium chloride + water + CO2 2CHl + Na2CO3 -> 2NaCl + H2O + CO2
       • Hydrochloric acid + calcium carbonate -> calcium chloride + water + CO2 2HCl + CaCO3 -> CaCl2 + H2O + Co2

4. Electrolysis

   • The decomposition of a compound using electrical energy
   • 1) The electricity must come from a D.C source - battery
     • 2) The liquid used to conduct the electricity is called the electrolyte
       • 3) The electricity is applied to the electrolyte by two electrodes
         • 4) The electrolyte contains the compound, this gets broken down into 2 parts
           • 5) The component parts are released as atoms or molecules - often a gas
           • Chlorine (Cl2)
             • Test: Bleaches damp litmus paper, turns it white
             • Electrolysis of salt water produces chlorine
               • Uses: 1) To treat water supplies - kills bacteria
                 • 2) To manufacture bleach
                   • 3) To make polymers - PVC
             • Electrolysis of water
               • Hydrogen
                 • Oxygen
                   • Test: Relights a glowing splint
       • HCL
         • Hydrogen (H2)
           • Test: Makes a "squeaky pop" with a lighted splint
         • EXPERIMENT No. 1