acids alkalis and titration

• Experiment 1


  1. Pour 20 cm3 of aqueous sodium hydroxide into a conical flask and record temperature

  2. Add 5 cm3 of solution X to the conical flask

  3. Stir the mixture with the thermometer and record the temperature

  4. Add further 5 cm3 volumes of solution X and stir with the thermometer, recording the temperature after each addition

  5. Stop when a total of 40 cm3 of solution X has been added
• Experiment 2


  1. Empty the burette and rinse it first with water and then with solution Y

  2. Repeat the experiment using solution Y
• Experiment 1 - Solution X


  • Volume in cm3 of solution X added
  • Temperature in °C
• Plot the results for Experiment 1 on the grid, drawing a straight line of best fit through the first three points and a second straight line of best fit through the last six points, ensuring the two straight lines cross
• Volume of solution X that will produce the maximum temperature rise when added to 20 cm3 of the aqueous sodium hydroxide

  Volume of solution X
• Maximum temperature rise


  Temperature rise
• The student rinsed the burette first with water, and then with solution Y, before performing Experiment 2
• The maximum temperature rise in Experiment 2 was less than that in Experiment 1
• Polystyrene cup


  Advantage over glass beaker
• Temperature change in °C

  • Before adding aqueous sodium hydroxide
  • After adding aqueous sodium hydroxide
• Plot the results on the grid, drawing a straight line of best fit through the first four points, and another straight line of best fit through the last three points, extending both lines so that they cross each other
• Point where the lines cross

  • Temperature of the mixture
  • Volume of aqueous sodium hydroxide
• Titration method


  1. Add 25 cm3 of dilute hydrochloric acid to the polystyrene cup and record the steady temperature

  2. Add some aqueous sodium hydroxide and stir the mixture

  3. Record the maximum temperature of the mixture
• Phenolphthalein indicator colour change

  Colourless to pink
• Phenolphthalein indicator is better to use than universal indicator in this titration
• Burette readings


  • Before adding acid
  • After adding acid
  • Volume of acid added
• Concordant results are those volumes that differ from each other by 0.20 cm3 or less
• Average volume of acid

  Volume of acid
• Titration to find concentration of phosphoric acid


  1. Volume of sodium hydroxide solution added to conical flask

  2. Concentration of sodium hydroxide solution

  3. Average volume of phosphoric acid solution added from burette
• Concordant titration results are those within 0.20 cm3 of each other
• Value of x in FeSO4.xH2O


  Whole number