Acids + bases

• What does MASH stand for?


  metal + acid --> salt + hydrogen
• What does BASH2O stand for?


  Base + Acid —> Salt + water
• What does CASHOCO stand for?


  carbonate + acid -> salt + water + carbon dioxide
• What is an acid

  proton donor

  They have a PH between 0 and 6
• What is a base?

  proton acceptor

  They have a PH greater that 7
• Litmus paper red and blue


  Acid= red

  Alkali= blue
• Phenolphthalein


  Acid= colourless

  Alkali= pink
• Methyl orange


  Acid= red

  Alkali= yellow
• Solubility rules


  Common salts of sodium, potassium and ammonium = soluble

  
  

  Nitrates = soluble

  
  

  Common chlorides = soluble (except silver, chloride and lead chloride

  
  

  Common Sulfates = soluble (except lead, barium and calcium Sulfate

  
  

  Common carbonates = insoluble (except for sodium potassium and ammonium)

  
  

  Common hydroxides = insoluble (except sodium, potassium and calcium)
• Base


  A substance that reacts with acids to produce a salt and water

  
  

  Proton acceptor

  
  

  They are alkalis if they dissolve in water
• Alkalies


  Proton acceptors

  
  

  Undergo neutralisation reactions with acids

  
  

  Soluble bases
• Solubility curves


  A graph showing the relationship between solubility and temperature
• Excess base method (crystals) how to purify soluble salt


  - add excess base to acid (base salt and water present)

  
  

  - filter leftover water (water and salt present)

  
  

  - evaporate water to leave salt

  
  

  - soluble acid + insoluble salt = soluble salt + water
• Making a soluble salt (titrations) purify salts

  - use same amount if acid and base so there is none left over

  
  

  - called a titration

  
  

  - H2SO4 +2NaSO4 = NaSO4 + 2H2O
• Making an insoluble salt (green stuff) purify salts


  - mix reactants

  
  

  - filter the mixture

  
  

  - a solid product will be formed

  
  

  - wash with water then propanone

  
  

  - leave to dry in a warm place

  
  

  - soluble acid + soluble base = insoluble salt + water
• Titration method


  1.Titration - making a soluble salt

  25cm3 alkali measured into conical flask using pipette

  and add 4 drops of phenolpthalein

  2.Fill burette with acid

  3.Note initial reading

  4.Add acid and note final reading or amount used when

  the indicator changes colour

  5.Repeat without indicator using the volume required

  6.Carry out crystallization / allow the solution to

  crystallise in a warm dry place.
• Making copper sulphate crystals


  Making Copper Sulfate

  1. Measure out 30cm3 Sulfuric acid into a crucible.

  2. Place crucible over beaker and warm using a bunsen burner.

  3. Add copper oxide, stir, and keep adding until mixture no longer

  reacts

  4. Filter mixture

  5. Evaporate mixture over a water bath (see picture) until it starts

  to crystallise

  6. Allow mixttre to cool

  7. Filter and dry crystals on filter paper
• Insoluble salts method (green stuff)


  1 Measure 20 cm3 of sodium hydroxide into a 100 cm3 beaker.

  2 Add 20 cm3 of copper sulfate.

  3 Gently swirl the mixture and then filter through folded filter paper.

  Wash it through with distilled water.

  4. Add a "squirt" of propanone to wash away the water from the solid

  5. Once it has all filtered, remove the filter paper, and transfer the

  solid to a fresh piece of filter paper.

  6. Sandwich the solid between two pieces of filter paper and press to

  complete the drying process. The solid is the insoluble salt.
• Copper carbonate + hydrochloride acid =


  Copper chloride + carbon dioxide + water
• Potassium Carbonate + hydrochloride acid =


  Potassium chloride + carbon dioxide + water
• Sodium carbonate + sulphuric acid =


  Sodium Sulfate + carbon dioxide + water
• Magnesium carbonate + sulphuric acid =


  Magnesium Sulfate + carbon dioxide + water
• What can metal oxides, metal hydroxides and ammonia act as?


  bases