RP 09 Investigating pH changes

• What is an acid?

  A proton donor
• What is a base?

  A proton acceptor.
• What is an alkali?

  A base that dissolves in water
• Why are acid-base indicators used?

  To detect whether a reaction reaches completion usually by the presence of a colour change
• Why does a pH meter need to be calibrated?

  So that the pH values for each pH readings are accurate
• How can you investigate how a weak acid's pH changes upon the addition of a strong base?

  Add 2cm^3 of NaOH from a burette to ethanoic acid, in a conical flask. Continue adding 2cm^3 of NaOH, measuring the pH every time
• Why is it important to stir the resulting solution?

  So all acid and base is thoroughly mixed, so the pH doesn't significantly vary throughout the solution as this would give an inaccurate reading.
• How would you analyse this data?

  • Plot a geaph of measured pH values (y-axis) against volume of NaOH solution added (x-value)
  • What is the shape of the curve?