CRP2

• titrations are used to find out exactly what volume of acid or alkali is needed to neutralise an acid or an alkali and this can be used to find out the concentration of the acid or alkali
• It is important to be looking at eye level during the titration to avoid mistakes.
• The volume of acid needed to neutralise the alkali is calculated by subtracting the final volume of the acid from the initial volume of the acid.
• The titration process is repeated and a mean is found to increase accuracy and ignore any anomalous results.
• titration method - to find the concentration of an alkali - using a pipette and a pipette filler to add a set volume of alkali to a conical flask and 2-3 drops of indicator. Next use a funnel to fill a burette with an acid of known concentration. Record the initial volume of the acid. Add the acid to the alkali slowly especially towards the end, regularly swirling the conical flask. The indicator will change colour when all the acid is neutralised.
• use single indicator for titrations so that the colour suddenly changes colour at the end point and not gradually
• Concordant results are results within 0.2 cm³ of each other.
• the first titration you do should be a rough titration to get an approximate idea of where the solution changes colour
• what is a titration?

  an experimental technique to find the unknown concentration of an acid or alkali
• the function of the pipette is to accurately measure a volume of alkali or acid, the function of the conical flask is to contain the liquid from the pipette, the function of the burette is to add acid or alkali to the conical flask and the function of the white tile is to be placed under the conical flask to make the colour change more apparent

  A) burette

  B) conical flask

  C) white tile

  D) pipette

  
• why must you constantly swirl the conical flask when adding in the acid or alkali from the burette?

  to ensure it is evenly distributed so the colour change occurs as soon as neutralisation takes place
• why must indicator be added to the conical flask?

  to we can tell when the acid has neutralised the alkali or visa versa as there will be a distinct colour change ~
• where do you place the acid / alkali of known concentration?

  in the burette
• what colour is phenolphthalein in acids?

  colorless
• what colour is the single indicator phenolphthalein in alkalis?

  pink
• what colour is the single indicator litmus in acids?

  red
• what colour is the single indicator litmus in alkalis?

  blue
• what colour is the single indicator methyl orange in acids?

  red
• what colour is the single indicator methyl orange in alkalis?

  yellow
• Which type of acids do i need to know how to do a titration for?

  only strong acids - only nitric acid, sulfuric acid and hydrochloric acid