Double displacement: making a silver chloride precipitate

Objectives

• Carry out a double displacement (precipitation) reaction.
• Separate an insoluble solid by filtration.

Theory

In a double displacement reaction two compounds exchange ions. When one of the new combinations is insoluble it appears as a precipitate. Silver chloride is insoluble in water, so mixing any soluble chloride with silver nitrate gives a white precipitate — the standard test for chloride ions.

AgNO₃ + NaCl → AgCl↓ + NaNO₃

Procedure

1. Put on your safety goggles and lab coat.
2. Place a beaker on the bench and add about 30 mL of distilled water.
3. Dissolve about 1 g of sodium chloride in the water.
4. Add about 20 mL of silver nitrate solution.
5. Observe the precipitate.
6. Place a funnel with filter paper and a second beaker on the bench.
7. Filter the mixture into the second beaker.

Precautions

• Silver nitrate stains skin and clothing black. Wear goggles and avoid contact.

Subject

Chemistry

Grade

9–10

Chapter

Chemical Reaction (Nepal National Curriculum (CDC), grade 10)

Difficulty

Medium

Duration

20 min

Safety level

Medium

Version

1.0

Apparatus

• Beaker (250 mL)
• Funnel and filter paper

Chemicals

• Distilled water H₂O
• Sodium chloride NaCl
• Silver nitrate solution AgNO₃ Stains skin