C3

Donors and Acceptors

• H+ ions form when acid is dissolved in water, making them proton donors
• OH- ions formed when alkali dissolves in water, making them proton acceptors
• This means when they combine they produce water, a neutral substance!!

Strengths

• Strong acids and alkalis are fully ionised in water
• Weak acids and alkalis are not
• Their strength is determined by there pH, the conc. H ions in a solution

Titrations

• Acid + Alkali is a neutralisation reaction
• It also produces a salt
• The precise volumes of acid and alkali needed can be measured with titrations
• TITRATION:
  • Measure known vol. of alkali into conical flask with pipette
  • Add indicator to flask
  • Put acid into burette. Record starting volume
  • Open tap to add acid to alkali drop by drop, swirling flask to mix the two
  • Keep adding until indicator changes
  • 

Indicators

• S Acid + S Alkali ---> Any
• S Acid + W Alkali---> Phenolphthalein
• W Acid + S Alkali ---> Methyl Orange

Titrations Calculations

• Step 1 - Write down all you know, e.g. vol. conc. moles
• Step 2- Write down as much of the equation as you know
• Step 3- Calculate no. of moles in known substance... Conc. x Vol.
  • Volume must be in dm³ (divide by 1000)
• Step 4- Calculate no. of moles in unknown substance
  • Use ratio from earlier equation
• Step 5- Work out conc. or vol. of unknown substance (ensure the use of dm³)

Endo/Exo

• Bendy Mexicans
• 

Measuring energy change