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Better Equipped Practical Teaching Guides
A curriculum-linked GCSE Chemistry practical guide to investigating the reactivity series using displacement reactions, featuring troubleshooting, retrieval practice, exam questions, differentiation and advanced evaluation support.
Teacher note: This resource is provided as a practical support guide to accompany laboratory equipment. Teachers should adapt procedures and risk assessments to suit their curriculum requirements, examination-board specifications and local laboratory policies.
In this investigation, students compare the reactivity of different metals by placing them into solutions containing metal ions and observing whether a displacement reaction occurs. A more reactive metal displaces a less reactive metal from its compound, producing visible evidence such as a solution-colour change, a new metal coating or another change to the original metal surface.
Each group tests the same assigned metal in all four solutions. By recording and comparing observations, then pooling the class results, students can determine the relative reactivity of the metals and construct the experimental order magnesium > zinc > iron > copper.
Core enquiry question: How can reactions between solid metals and metal ions in solution be used to place magnesium, zinc, iron and copper in order of reactivity?
More reactive metals lose electrons more readily than less reactive metals. When a more reactive metal is added to a solution containing ions of a less reactive metal, the solid metal loses electrons and enters the solution as ions. The less reactive metal ions gain electrons and form solid metal.
A solid metal can displace the ions of a metal below it in the reactivity series. It cannot displace ions of the same metal or a metal above it.
The more reactive solid metal is oxidised because it loses electrons. The less reactive metal ions are reduced because they gain electrons.
OIL RIG: Oxidation Is Loss of electrons; Reduction Is Gain of electrons.
In sulfate solutions, sulfate ions remain unchanged. They are spectator ions and are omitted from the net ionic equation.
The series predicts whether displacement is possible. The practical conclusion must still be based on observations made under clean, controlled conditions.
Interpreting no visible change: under suitable conditions, it shows that the added metal was not more reactive than the metal ions present. The solid may be the same metal or a less reactive metal.
Group allocation: provide four similar pieces of one assigned metal to each group.
Surface preparation: abrade each metal immediately before use and remove loose residue. Aluminium, when used as an extension metal, must be freshly abraded because its oxide layer may prevent the expected displacement.
Overall risk level: Low. The guide states that this practical presents a low level of risk when standard laboratory procedures are followed. Schools should complete their own task-specific risk assessment in accordance with local procedures and check the supplier SDS for the actual concentration of each solution.
| Example hazard | Example risk | Example control measure |
|---|---|---|
| Copper(II) sulfate solution - concentration: ______ | May be harmful or irritating depending on concentration. Risks include splash exposure to eyes or skin, accidental ingestion from contaminated hands, and environmental harm from copper-containing waste. | Check the supplier SDS for the actual concentration. Use small quantities. Wear eye protection. Keep containers clearly labelled and stoppered when not dispensing. Use a dedicated labelled pipette. Avoid skin contact and hand-to-mouth transfer. Do not eat or drink. Wash hands after the practical and dispose of waste using the labelled containers provided. |
Unexpected bubbling: gas is not normally a product of these metal-ion displacement reactions. Stop, report and check for acidic contamination or another side reaction rather than treating bubbling as normal displacement evidence.
Label four tubes copper(II) sulfate, iron(II) sulfate, zinc sulfate and magnesium sulfate.
Add the same measured volume, for example 5.0 cm3, of the correct solution to each labelled tube. Use a separate clean dispensing pipette for each solution.
Each group receives four pieces of one assigned metal: magnesium, zinc, iron or copper. The pieces should have similar exposed surface areas.
Abrade each piece gently with emery paper immediately before the reaction. Remove loose residue without touching the cleaned surface. Place one piece of the assigned metal into each of the four solutions and start the timer as soon as the first piece is added.
Important: do not use a different solid metal in each tube. Each group tests the same assigned metal against all four solutions.
Observe each tube immediately after adding the metal, after approximately one minute and after five minutes. Keep the reaction time the same for all tubes.
Record the initial solution colour, any change in solution colour, any coating or new solid, any change to the original metal and whether the solution remains unchanged.
Bubbling: this is not normally a product of the metal-ion displacement reaction. Unexpected bubbling may indicate contamination, acidity or another side reaction.
Use forceps to remove the pieces. Place them in the labelled used-metal tray specified by the technician.
Decide whether each observation supports displacement. Combine the results from all groups to complete the full class matrix and use the pattern to determine the reactivity order.
Keep the comparison standardised: do not shake the tubes unless a standardised mixing procedure has been deliberately included.
| Assigned metal | Solution | Initial appearance | Change to solution | Deposit or metal-surface change | Other observations |
|---|---|---|---|---|---|
| Copper(II) sulfate | |||||
| Iron(II) sulfate | |||||
| Zinc sulfate | |||||
| Magnesium sulfate |
| Metal added | CuSO4 | FeSO4 | ZnSO4 | MgSO4 |
|---|---|---|---|---|
| Magnesium | Displacement | Displacement | Displacement | No displacement |
| Zinc | Displacement | Displacement | No displacement | No displacement |
| Iron | Displacement | No displacement | No displacement | No displacement |
| Copper | No displacement | No displacement | No displacement | No displacement |
Reaction matrix key: evidence supports displacement when a reaction is observed; no displacement means no displacement was observed under the stated conditions.
The initial solution is blue because it contains hydrated Cu2+ ions.
The initial solution is pale green.
The solution is colourless. Magnesium can displace zinc, but evidence may be limited to a dull-grey coating or another surface change. Use a white background and good lighting.
No displacement is expected with magnesium, zinc, iron or copper. Magnesium in magnesium sulfate acts as a same-metal control.
Record observations before conclusions: write what changed first, then state whether the evidence supports displacement. A tick or cross alone removes the raw evidence needed to justify the conclusion.
Magnesium reacting with copper(II) sulfate is a clear worked example. Magnesium is more reactive, so it displaces copper from solution.
Word equation
magnesium + copper(II) sulfate → magnesium sulfate + copper
Balanced equation
Mg(s) + CuSO4(aq) → MgSO4(aq) + Cu(s)
Net ionic equation
Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
Oxidation
Mg(s) → Mg2+(aq) + 2e-
Reduction
Cu2+(aq) + 2e- → Cu(s)
Magnesium atoms lose electrons. Copper(II) ions gain electrons. Sulfate ions remain unchanged and are omitted from the ionic equation.
Higher Tier or board-dependent explanation: electrons are transferred at the metal surface from atoms of the more reactive metal to ions of the less reactive metal.
Identity of the solid metal and identity of the metal ions in solution.
Initial and final solution appearance, a new metal deposit, changes to the original metal and whether evidence supports displacement.
Solution concentration and volume, temperature, observation time, exposed metal area, cleaning, immersion depth, vessel and mixing.
Repeat tests or compare independent groups. Report consistency, for example, “displacement observed in three out of three repeats”.
How the variables are compared: in a single focused comparison, either the solid metal or the solution can be kept fixed while the other is changed. Across the complete class matrix, both identities are varied systematically.
| Possible issue | Effect on the evidence | Improvement |
|---|---|---|
| Oxide or contamination on the metal | A predicted reaction may appear weak or absent. | Abrade immediately before use and do not touch the cleaned face. |
| Different exposed metal areas | Reaction rate or visible intensity differs between tests. | Standardise exposed surface area. |
| Inaccurate solution volumes | Comparisons are less fair. | Use a graduated pipette, syringe or measuring cylinder. |
| Cross-contamination | Unexpected reactions or colours may appear. | Use a separate labelled pipette for each solution. |
| Different reaction times | Some tubes have more time to show a change. | Use one timer and a fixed observation schedule. |
| Incorrectly labelled tubes | Results may be assigned to the wrong reaction. | Label all tubes before dispensing the solutions. |
| Galvanised iron nail | The zinc coating can produce misleading results. | Use verified uncoated and ungalvanised iron. |
| Deposit difficult to see | Displacement may be missed. | Use a white background, good lighting and a fresh standardised strip. |
The investigation is valid when observed differences can reasonably be attributed to the identities of the metal and metal ions rather than uncontrolled differences in concentration, volume, temperature, time, surface area or surface condition.
A solid metal that displaces another metal from its ions is more reactive than the displaced metal. Combining several comparisons gives magnesium > zinc > iron > copper.
A single no-reaction result cannot position a metal precisely; several comparisons are needed.
Test a coded metal against selected known metal-ion solutions and use the pattern of reactions and no reactions to place it relative to magnesium, zinc, iron and copper. Students should make predictions, choose informative comparisons, control solution volume, concentration, time and exposed surface area, record raw observations, justify the final position and explain any ambiguous result.
| Problem | Possible cause | Action |
|---|---|---|
| A predicted reaction is not observed | Oxide coating, dirty metal, wrong solution or insufficient time | Check labels, abrade a fresh piece and repeat for the fixed observation time. |
| A colour change is difficult to see | Low concentration, small change or a colourless product solution | Compare against a white background and inspect the metal surface. |
| A deposit is difficult to identify | The layer is thin or similar in colour to the starting metal | Use good lighting, a magnifier where available and a fresh standardised strip. |
| An unexpected reaction occurs | Cross-contamination or mislabelling | Replace the solution and use dedicated pipettes. |
| Groups obtain different results | Different surface areas, cleaning methods or reaction times | Standardise the method and repeat. |
| Iron behaves like zinc | The nail may be galvanised | Use verified uncoated iron. |
| Bubbling occurs | Possible acidic contamination or another side reaction | Stop, report and check the solutions; do not count bubbling as normal displacement evidence. |
| Misconception | Correction |
|---|---|
| Every metal reacts with every solution. | Only a metal more reactive than the metal represented by the ions can displace it. |
| Blue colour means copper metal. | The blue colour is produced by Cu2+ ions in solution; copper metal is reddish-brown. |
| If nothing happens, the experiment failed. | No visible change can be a valid result under clean, controlled conditions. |
| No visible change always means the solid metal is less reactive. | It may be less reactive or it may be the same metal. |
| All displacement reactions produce bubbles. | Gas is not normally produced in these metal-ion displacement reactions. |
| A coating is only the original metal changing colour. | The coating may be a new solid metal deposited from the solution. |
When a no-change result is meaningful: the metal must be clean, the solutions correctly labelled and sufficient reaction time allowed.
Core content: relative reactivity, displacement reactions, observations and predictions, and balanced symbol equations.
Higher Tier or board-dependent content: electron transfer, oxidation and reduction half-equations, ionic equations and spectator ions.
Relevant to reactivity and displacement content in AQA, OCR and Pearson Edexcel GCSE Chemistry. Teachers should verify the precise practical status and tier requirements against the current specification being taught.
Zinc is more reactive than copper. Zinc atoms lose electrons more readily than copper atoms, so zinc can reduce Cu2+ ions to copper metal.
The more reactive solid metal is oxidised.
Evidence may include a solution-colour change and/or the formation of a new solid metal deposit.
Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
Cleaning removes oxide and contamination that could prevent the solution contacting the metal surface.
In each comparison, solution concentration and volume, temperature, reaction time, exposed metal area, cleaning method and immersion depth are kept consistent. Across the full class matrix, the metal identity and metal-ion identity are the two factors deliberately varied.
Place magnesium ribbon into copper(II) sulfate solution. Within minutes, students should observe the blue solution fading, a copper coating forming and the magnesium dissolving.
| Activity | Suggested time |
|---|---|
| Introduction, prediction and prior knowledge | 8 minutes |
| Safety briefing and method allocation | 5 minutes |
| Apparatus setup | 5 minutes |
| Reactions and timed observations | 15 minutes |
| Cleanup and waste collection | 5 minutes |
| Pooling and interpreting class results | 12 minutes |
| Plenary and examination questions | 10 minutes |
Galvanising coats steel with zinc. The coating forms a barrier and zinc can provide sacrificial protection if the coating is scratched.
Reactivity and reduction help explain why some metal oxides can be reduced by carbon while more reactive metals require electrolysis.
Differences in the tendency of metals to lose electrons can be used to create a potential difference.
Reactivity affects the suitability of metals for construction, transport and engineering.
The series helps explain why some metals, such as gold, resist corrosion while metals such as iron rust more readily and often require protection.
Which metal loses electrons? Which process is oxidation? What does a displacement reaction reveal about relative reactivity?
| Plenary question | Expected answer |
|---|---|
| Why does magnesium displace copper? | Magnesium is more reactive. |
| Why does copper not displace magnesium? | Copper is less reactive. |
| What does displacement tell us? | The relative reactivity of metals. |
| Which metal loses electrons? | The more reactive metal. |
| Which process is oxidation? | Loss of electrons. |
Browse school chemistry equipment for test tubes, racks, measuring apparatus, forceps, eye protection and practical-laboratory consumables.
Browse chemistry equipmentThis guide was written and reviewed by Better Equipped's technical team and further reviewed by former A Level Science Teachers. Our technical team draw on experience supplying practical science equipment to schools, colleges, laboratories and science departments throughout the UK. They include ex-school laboratory technicians and are here to support schools, colleges and laboratories. If you have feedback on this guide, we'd love to here it so please contact us. Don't forget we will be regularly updating our guides and resources on our Better-Resources Hub. If you would like us to cover a particular subject matter in these guides or have some top tips you'd like to share then again we'd love to hear from you.
Last reviewed and updated: August 2026
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