require practical 1


how to make a standard solution

  • weigh out an accurate mass of a solid in a clean dry beaker 
  • add enough deionised water to dissolve the solid, stirring with a glass rod 
  • transfer the solution with rinsing to a 250 cm3 volumetric flask using a funnel 
  • rinse the beaker and glass rod with deionised water and add to the volumetric flask 
  • makeup to the mark by adding deionised water until the bottom of the meniscus is on the mark 
  • stopper the flask and invert to mix thoroughly 
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how is titration carried out

  • rinse the burette with the solution you are filling it with. discard rinsings and fill burette 
  • rinse a pipette with the solution you are going to pipette into the conical flask. using a pipette and pipette filler transfer 25 cm3 of this solution into a conical flask 
  • add 2-3 drops of a suitable indicator to the conical flask 
  • add the solution from the burette, with constant swirling, until the indicator changes colour. this is trial titration 
  • to reduce the effect of random error on titration results, repeat the titration to achieve 2-3 concordant result, adding the solution dropwise near the endpoint.
  • calculate the mean titre from the concordant results
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what titrations are methyl orange indicator useful

Red in acid 

Orange in alkali 

strong acid-strong base

strong acid-weak base

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what titrations are Phenolphthalein useful in?

acid- Colourless

Alkali- Pink 

strong acid- strong base

weak acid - strong base 

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how to ensure solution from pipette reacts with fl

sometimes the solution from the pipette can run down the side of the conical flask 

swirling the conical flask ensures mixture 

draining deionised water down the sides ensures mixture - solutions are diluted but the amount in moles present in the pipetted solution will have not been changed 

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how would you carry out a back titration

e.g. indigestion tablet ( calcium carbonate in it )

  • tablet weighed in a beaker
  • volume of acid added 
  • solution added to volumetric flask with rinsings and made uo to 250cm3 
  • portions of this solution can be titrated to determine the mass of Calcium carbonate in the indigestion tablet 
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