Acids and Bases

Acids and Bases

1. Properties

   • Acids contains H+ ions
     • Proton donor
     • Have a pH of 1-6
     • Acids turn blue litmus paper red
     • The Universal indicator scale shows that acids are red, yellow or orange.
       • Red is a strong acid
       • methyl orange indicators- turns yellow with alkali and orange with acid
       • Phenolphtahalien turns colourless in acids and pink in alkalis
     • Strong acids contain mainly H+ ions whereas weak acids contain less
   • Bases/alkalis contain OH- ions
     • Proton acceptors
     • Have a pH of 8-14
     • alkalii's turn red litmus paper blue
   • Water is neutral and has a pH of 7

2. Metal salts

   • are all alkaline
   • created by reacting a metal and an acid
     • Hydrogen gas is produced as a by product
   • Can be made by titration, precipitation and neutralisation
     • Titration: used to find the amount of acid needed to neutralise a known amount of alkali or vice versa
   • acids plus metal oxides or hydroxides makes a metal salt an water
   • acids plus metal carbonates make carbon dioxide, metal salt and water
   • naming salts
     • nitric acid- makes nitrates
     • hydrochloric acid makes chlorides
     • sulphuric acid makes sulphates

3. Types of acids

   • Hydrochloric acid HCl is a strong acid
   • Sulphuric acid H2SO4 is a strong acid
   • ethanoic acid is a weak acid which is also called vinegar
     • Infact all carboxylic acids are weak acids
   • nitric acid HNO3 iis a strong acid

4. Calculations

   • Concentration in moles/dm3 is the number of moles divided volume in dm3

5. Solubility rules

   • all nitrates are soluble
   • all chlorides are soluble except for silver and lead
   • all sodium, potassium and ammonium salts are soluble

6. Neutralisation

   • occurs when H+ ions and OH_ ion fully dissasociate

7. Where do we find them?

   • beestings
     • can be neutralised with baking soda
   • ctric acids found in citrus fruits
   • Sulphur dioxide reacts with water in the clouds to make acid rain
   • use quicklime and slaked lime to neutralise acidic soil

8. Tests for cations and anions

   • ts for carbonates - add HCl, if CO2 is produced it will turn limewater milky
   • chloride, bromide and iodide ions: acidify with dilurte acid and add barium nitrate
     • Chrloride: white ppt
     • Bromide cream ppt
     • Iodide: yellow ppt
   • Fe2+ and Fe 3+ ": add NaOH, grreen ppt for Fe2+ and Red/brown ppt for Fe3+

9. oxides

   • amphroteric oxides are act as both acids and bases
   • basic oxides are always metal oxides

10. Safety

    • strong acids and bases are corrosive