AQA A Level Chemistry复习笔记8.2.1 Required Practical 11

Required Practical 11: Carry out simple test-tube reactions to identify transition metal ions in aqueous solution

• This practical covers a number of key laboratory skills
  • use water bath or electric heater or sand bath for heating
  • use laboratory apparatus for a variety of experimental techniques
  • safely and carefully handle solids and liquids, including corrosive, irritant, flammable and toxic substances

   

• The key to success in Required Practical 11 is following instructions carefully and recording coherent detailed observations of what you see
• The aim of the practical is to record the reactions of three unknown solutions, L, M and N

Key steps in the procedurePart 1

• 10 drops of solution L are added to a clean test tube
• Drops of dilute sodium hydroxide are added until in excess (i.e. you have exceeded 10 drops)
• Observations are recorded
• This procedure is then repeated with solution M and N

Part 2

• The test tubes from part 1 are place in a beaker of hot water for around 10 minutes

Part 3

• 10 drops of sodium carbonate solution are added to a clean test tube
• 10 drops of solution L are then added to the test tube and observations made
• The procedure is repeated with solution M and N

Part 4

• 10 drops of solution L are added to a clean test tube
• 10 drops of silver nitrate solution are then added to the test tube and observations made
• The procedure is repeated with solutions M and N and the tubes left to rest for around 10 minutes

Required Practical 11: Specimen Results Table Parts 1 & 2

Required Practical 11: Specimen Results Table Part 3

Required Practical 11: Specimen Results Table Part 4

Required Practical 11: Identities of solutions L, M and N

Practical Tip

• Always use clean test tubes and pipettes as the tests are very sensitive and you don't want to cross-contaminate the solutions
• It's a good idea to label your test tubes to avoid confusing ones that have the same appearance, especially when they are in a water bath and not arranged in a test tube rack
• To observe colour changes more clearly, using a white background such as a piece of paper can help

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