IB DP Chemistry: SL复习笔记8.2.1 Acid-base Titrations

Acid-Base Titrations

  • The steps involved in performing a titration and titration calculation are outlined in Topic 1.2.9 Titrations
  • Acid-base titrations follow the same steps and are used to find the unknown concentrations of solutions of acids and bases
  • Acid-base indicators give information about the change in chemical environment
  • They change colour reversibly depending on the concentration of H+ ions in the solution
  • Indicators are weak acids and bases where the conjugate bases and acids have a different colour
  • Many acid-base indicators are derived from plants, such as litmus

Common Indicators Table

8.1.5-Common-Indicators-Table

  • A good indicator gives a very sharp colour change at the equivalence point
  • In titrations is it not always possible to use two colour indicators because of this limitation, so for example litmus cannot be used successfully in a titration
  • When phenolphthalein is used, it is usually better to have the base in the burette because it is easier to see the sudden and permanent appearance of a colour (pink in this case) than the change from a coloured solution to a colourless one

Exam Tip

Make sure you learn the colours of the common acid-base indicators

 

 

 

 

 

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