Standard level
Displacement is the process of removing one component and replacing it with another. In this case the displacement is a redox reaction where an active metal displaces a less acitve metal from a solution of one of its salts.
Background
Zinc is a more reactive metal than copper and will displace copper from a solution containing copper ions. Copper(II) sulfate(aq) contains free Cu2+ ions, these pick up electrons from the zinc to form copper metal and in the process zinc ions, Zn2+ are formed.
reaction between zinc and copper(II) sulfate
Zn(s) + CuSO4(aq) → CuSO4(aq) + Cu(s)
The redox reaction
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
Chemicals
- Copper(II) sulfate(aq), 1.0 mol dm-3
- Zinc powder
Apparatus
- Polystyrene beaker
- Glass beaker, 250ml
- Thermometer or temperature probe
- Magnetic stirrer
- Pipette, 25ml
- Electronic balance
- You are provided with a solution of copper(II) sulfate, concentration 1.0 mol dm-3.
- Using a pipette, transfer 25ml of the copper(II) sulfate solution into a pre-weighed beaker. Reweigh the beaker and contents.
- Weigh out about 3g of zinc powder (the actual mass is not critical, it is an excess)
- Record the temperature of the solution and repeat the reading every 30 seconds.
- On the 120 second mark, add the zinc powder quickly with stirring using the thermometer. Continue recording the temperature every 30 seconds until a total of 10 minutes have passed.
- Dispose of the residue in the receptacle provided.
- Repeat the procedure twice more.