EL 9 

• ==Acid=== contains hydrogen (H+) ions when dissolved in water. Also known as a proton donor
• ==Base=== the opposite of an acid. A proton acceptor
• ==Alkalis=== a base that dissolves in water, contains hydroxide ions (OH-) when dissolved in water
• ==Neutralisation=== in neuralisation reactions between an acid and an alkali, the hydrogen ions react with hydroxide ions to produce water and a salt
• ==Oxonium ion=== a reaction between acid and water produces the oxonium ion H3O+

  - The lone pair on the O forms a dative covalent bonds to H+

  - Water behaves as a base and the oxonium ion can act as an acid

• ==Concentration=== moles/volume
• - Normally in mol/dm^3
• We can use how concentration is linked to moles to help determine the concentration of unknown samples. Experimentally we do this by titration
• We use titrations to find out the unknown concentration of substances
• ==Concordant titres=== titration results that are in 0.1cm^3 of each other. The mean of these can then be used in calculations. The titration must be repeated until 2 concordant titres are achieved.
• You always have to measure from the bottom of the meniscus
• ==% error= (uncertainty/volume recorded) times 100==
• ==Overall % error of practical= % error 1 + % error 2 …==

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