Report for Experiment 12: Single Displacement Reactions
A report for experiment 12 single displacement reactions connects visible laboratory evidence with the activity series and oxidation-reduction chemistry. The central chemical idea is that a free element can replace an ion in aqueous solution only when the free element is more active and therefore more readily oxidized.
Experimental focus
Experiment 12 is treated as a General Chemistry investigation in which clean metal strips are placed into aqueous metal-salt solutions. The report describes color changes, metallic deposits, and no-reaction cases, and it relates those observations to balanced chemical equations.
Core claim
A single displacement reaction occurs when the solid metal is above the dissolved metal ion in the activity series. The solid metal is oxidized, the dissolved metal ion is reduced, and a new solid metal may appear as a coating, crystals, or powder.
General reaction pattern
The usual pattern for metal displacement in aqueous solution is:
The reaction is spontaneous only when metal \(\mathrm{A}\) is more active than metal \(\mathrm{B}\). The spectator ions, such as \(\mathrm{SO_4^{2-}}\) or \(\mathrm{NO_3^-}\), remain dissolved and do not appear in the net ionic equation.
Theoretical basis
Single displacement reactions are redox reactions. The metal atom that enters solution undergoes oxidation, and the metal ion that becomes a solid undergoes reduction. For zinc placed in copper(II) sulfate solution, the balanced molecular equation is:
Sulfate is a spectator ion, so the net ionic equation is:
Oxidation half-reaction
\[ \mathrm{Zn}(s) \rightarrow \mathrm{Zn}^{2+}(aq) + 2e^- \]
Zinc changes from oxidation state \(0\) to \(+2\), so zinc is the reducing agent.
Reduction half-reaction
\[ \mathrm{Cu}^{2+}(aq) + 2e^- \rightarrow \mathrm{Cu}(s) \]
Copper changes from oxidation state \(+2\) to \(0\), so copper(II) ion is the oxidizing agent.
Report structure
| Section of report | Scientific content | Expected standard |
|---|---|---|
| Title | Experiment 12: Single Displacement Reactions | The title names the reaction class and the laboratory context clearly. |
| Purpose | Relationship between metal activity, observable evidence, and reaction prediction | The purpose states that metal displacement depends on relative activity and electron transfer. |
| Theory | Activity series, oxidation, reduction, spectator ions, balanced equations | The theory explains why some metal-salt combinations react and others do not. |
| Data and observations | Color change, solid formation, coating, solution appearance, no-reaction evidence | Observations are descriptive and separated from interpretation. |
| Discussion | Balanced molecular equations, complete ionic equations, net ionic equations, activity-series ranking | Each claim about reaction or no reaction is supported by both evidence and chemical reasoning. |
| Conclusion | Summary of supported reactions and activity trend | The conclusion connects the observations to the activity series without overstating uncertain results. |
Representative observations and equations
The following model table gives a rigorous form for reporting typical Experiment 12 results. Actual laboratory observations may vary slightly with metal cleanliness, solution concentration, and reaction time.
| Reaction system | Expected observation | Balanced molecular equation | Net ionic equation | Interpretation |
|---|---|---|---|---|
| Zinc metal in copper(II) sulfate | Reddish-brown copper coating forms; blue solution becomes paler. | \(\mathrm{Zn}(s)+\mathrm{CuSO_4}(aq)\rightarrow\mathrm{ZnSO_4}(aq)+\mathrm{Cu}(s)\) | \(\mathrm{Zn}(s)+\mathrm{Cu}^{2+}(aq)\rightarrow\mathrm{Zn}^{2+}(aq)+\mathrm{Cu}(s)\) | Zinc is more active than copper, so displacement occurs. |
| Iron metal in copper(II) sulfate | Copper-colored solid appears; solution may shift toward pale green from \(\mathrm{Fe^{2+}}\). | \(\mathrm{Fe}(s)+\mathrm{CuSO_4}(aq)\rightarrow\mathrm{FeSO_4}(aq)+\mathrm{Cu}(s)\) | \(\mathrm{Fe}(s)+\mathrm{Cu}^{2+}(aq)\rightarrow\mathrm{Fe}^{2+}(aq)+\mathrm{Cu}(s)\) | Iron is more active than copper, so iron atoms reduce \(\mathrm{Cu^{2+}}\). |
| Copper metal in silver nitrate | Silver crystals form on copper; solution becomes blue as \(\mathrm{Cu^{2+}}\) forms. | \(\mathrm{Cu}(s)+2\mathrm{AgNO_3}(aq)\rightarrow\mathrm{Cu(NO_3)_2}(aq)+2\mathrm{Ag}(s)\) | \(\mathrm{Cu}(s)+2\mathrm{Ag}^{+}(aq)\rightarrow\mathrm{Cu}^{2+}(aq)+2\mathrm{Ag}(s)\) | Copper is more active than silver, so silver ions are reduced to silver metal. |
| Copper metal in zinc sulfate | No reliable color change or solid formation. | No reaction | No reaction | Copper is less active than zinc, so copper cannot displace \(\mathrm{Zn^{2+}}\). |
| Silver metal in copper(II) sulfate | No visible reaction under normal classroom conditions. | No reaction | No reaction | Silver is less active than copper, so silver cannot reduce \(\mathrm{Cu^{2+}}\). |
Complete ionic and net ionic reasoning
Aqueous salts that are strong electrolytes are represented as separated ions in the complete ionic equation. For zinc reacting with copper(II) sulfate, the complete ionic equation is:
The sulfate ion appears unchanged on both sides and is removed as a spectator ion:
The remaining net ionic equation expresses the actual chemical change:
Activity-series interpretation
The activity series ranks metals according to their tendency to lose electrons. A simplified portion useful for this report is:
Metals on the left are more easily oxidized than metals on the right. Therefore, \(\mathrm{Zn}\) can displace \(\mathrm{Cu^{2+}}\), \(\mathrm{Fe}\) can displace \(\mathrm{Cu^{2+}}\), and \(\mathrm{Cu}\) can displace \(\mathrm{Ag^+}\). Copper cannot displace \(\mathrm{Zn^{2+}}\), and silver cannot displace \(\mathrm{Cu^{2+}}\).
Sample discussion paragraph
The observations support the activity-series prediction for single displacement reactions. Zinc placed in copper(II) sulfate produced a copper-colored coating and a fading blue solution, consistent with the reduction of \(\mathrm{Cu^{2+}}\) to \(\mathrm{Cu}(s)\) and the oxidation of \(\mathrm{Zn}(s)\) to \(\mathrm{Zn^{2+}}(aq)\). Copper placed in zinc sulfate showed no visible reaction, which is consistent with copper being below zinc in the activity series. The results therefore support the order \(\mathrm{Zn} > \mathrm{Fe} > \mathrm{Cu} > \mathrm{Ag}\) for the metals tested.
Sample conclusion
Experiment 12 demonstrates that single displacement reactions are controlled by relative metal activity. A reaction occurred when the solid metal was more active than the metal ion in solution, as shown by copper deposition from copper(II) sulfate and silver deposition from silver nitrate. No reaction occurred when the solid metal was less active than the dissolved metal ion. The observations, balanced equations, and net ionic equations all support the same redox interpretation.
Common errors in the report
| Error | Why it weakens the report | Correct treatment |
|---|---|---|
| Writing \(\mathrm{CuSO_4}\) as a reacting unit in the net ionic equation | The sulfate ion is a spectator ion in this reaction. | The net ionic equation contains \(\mathrm{Cu^{2+}}\), not the full formula \(\mathrm{CuSO_4}\). |
| Calling every color change a reaction | Color alone may come from contamination, lighting, or surface impurities. | Color change is strongest when paired with a new solid, coating, gas, or consistent ionic equation. |
| Balancing atoms but ignoring charge | Redox equations require both atom balance and charge balance. | The net ionic equation must conserve atoms and total charge. |
| Confusing oxidizing agent and reducing agent | The agent names refer to what the substance causes, not what happens to it. | The oxidized metal is the reducing agent; the reduced ion is the oxidizing agent. |
Safety and waste notes
Metal-salt solutions such as copper(II) sulfate and silver nitrate require careful handling because they can stain, irritate tissue, and harm aquatic systems. Solid metals and used solutions belong in the assigned inorganic waste container. Sink disposal is not appropriate unless the laboratory instructor specifically authorizes it under local rules.