Edexcel IGCSE Chemistry 复习笔记 2.6.3 Acid-Alkali Titrations

• Titrations are a method of analysing the concentration of solutions
• Acid-base titrations are one of the most important kinds of titrations
• They can determine exactly how much alkali is needed to neutralise a quantity of acid – and vice versa
• You may be asked to calculate the moles present in a given amount, the concentration or volume required to neutralise an acid or a base
• Titrations can also be used to prepare salts

How to carry out a titration

Performing a titration

Method:

1. Use the pipette and pipette filler and place exactly 25 cm³ sodium hydroxide solution into the conical flask
2. Place the conical flask on a white tile so the tip of the burette is inside the flask
3. Add a few drops of a suitable indicator to the solution in the conical flask
4. Perform a rough titration by taking the burette reading and running in the solution in 1 – 3 cm³ portions, while swirling the flask vigorously
5. Quickly close the tap when the end-point is reached (sharp colour change) and record the volume, placing your eye level with the meniscus
6. Now repeat the titration with a fresh batch of sodium hydroxide
7. As the rough end-point volume is approached, add the solution from the burette one drop at a time until the indicator just changes colour
8. Record the volume to the nearest 0.05 cm³
9. Repeat until you achieve two concordant results (two results that are within 0.1 cm³ of each other) to increase accuracy

Results:Record your results in a suitable table, e.g: