Practicaly q

Question 1

Silver cyanide can be precipitated from sodium cyanide solution by adding an excess of silver nitrate solution.

Describe how you would obtain a pure dry sample of silver cyanide from this mixture. (3)

Answer 1

• Filter
• Wash (the residue) with water
• Dry by pressing between filter paper

Question 2

Potassium manganate(VII) is oxidising and harmful.
Sodium ethanedioate is toxic.
Suggest safety precautions, other than eye protection, that should be taken when:
* filling the burette with potassium manganate(VII) solution
* dissolving the solid sodium ethanedioate in water. (2)

Answer 2

1. fill at/ below eye level
2. wear gloves

Question 3

Sodium ethanedioate is used to find the concentration of solutions of potassium manganate(VII) by titration.
State the colour change seen at the end point of each titration. (1)

Answer 3

colourless –> pink

Question 4

Give two practical steps needed before recording the initial burette reading. (2)

Answer 4

1. ensure jet is filled (x bubbles) (open tap to fill space below tap)
2. remove filter funnel