Activity Series Reference

This is one of nature's most clever protective tricks! Aluminium is indeed very reactive — almost as reactive as magnesium. But the moment a fresh aluminium surface is exposed to air, it reacts instantly with oxygen and forms a very thin (about 4 × 10−6 cm), tough, transparent layer of aluminium oxide (Al2O3). This oxide layer is non-porous and tightly stuck to the metal underneath, sealing it from further oxygen and moisture. So aluminium essentially protects itself with its own corrosion product — a phenomenon called passivation. 4 Al(s) + 3 O2(g) → 2 Al2O3(s) [protective layer]

Sodium is one of the most reactive metals known. If kept in open air, it reacts vigorously with both oxygen and the moisture present in the atmosphere, producing sodium hydroxide and hydrogen gas — and the reaction is so exothermic that the hydrogen often catches fire spontaneously! To prevent this, sodium is stored under kerosene oil, which is a non-reactive hydrocarbon liquid that does not allow air or water to reach the metal surface. The same precaution is followed for potassium and lithium. 2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g) ↑ (catches fire)

Gold (Au) and Platinum (Pt) sit right at the bottom of the activity series, meaning their tendency to lose electrons is extremely low. They do not react with oxygen, moisture, or even most acids under ordinary conditions. So when these metals are formed in the Earth's crust, they remain as free elements rather than as compounds. That is also why ancient gold ornaments unearthed today still shine — they have not corroded in thousands of years. Aqua regia (HNO3 : HCl :: 1 : 3) is one of the few reagents that can dissolve gold.

Yes, definitely. Iron is placed above copper in the activity series, so it is more reactive. When an iron nail is dipped into blue copper sulphate solution, the iron atoms lose electrons and pass into solution as Fe2+ ions, while the Cu2+ ions accept those electrons and get deposited as a brownish-red coating of copper on the nail. The blue colour of the solution gradually fades. This is a classic single displacement (redox) reaction we always demonstrate in class. Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)

Yes. Zinc is placed above copper in the activity series, so it is more reactive and easily displaces copper from copper sulphate. The blue colour of the solution slowly changes to colourless as Cu2+ is replaced by Zn2+, and a reddish-brown deposit of metallic copper appears on the surface of the zinc strip. This reaction is the basis of the famous Daniell cell used to introduce electrochemistry. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

Yes. Although copper is not very reactive overall, it is still placed above silver in the activity series. So when a copper wire is dipped into colourless silver nitrate solution, copper atoms lose electrons and go into solution as blue Cu2+ ions, while silver ions deposit as shiny silvery crystals on the wire — looking almost like a tiny silver tree. The solution slowly turns blue, confirming the reaction. Cu(s) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 Ag(s)

Yes. Magnesium is placed well above zinc in the activity series, so it is more reactive and readily displaces zinc from zinc sulphate solution. Magnesium dissolves to form magnesium sulphate, while zinc gets deposited as a grey solid. This reaction also releases some heat, making the test tube slightly warm — a clear sign of an exothermic redox reaction. Mg(s) + ZnSO4(aq) → MgSO4(aq) + Zn(s)

No. Copper is below iron in the activity series, so it is less reactive than iron. A less reactive metal can never displace a more reactive metal from its salt solution. If you dip a copper strip into ferrous sulphate solution, absolutely nothing happens — no colour change, no deposit, no temperature change. This reaction is not feasible, and we always write “No reaction” in such cases. Cu(s) + FeSO4(aq) → No Reaction

Yes. Zinc is placed above hydrogen in the activity series, so it can displace hydrogen from dilute non-oxidising acids like HCl and dilute H2SO4. When zinc granules are dropped into dilute HCl, brisk effervescence of colourless, odourless hydrogen gas is observed. Bring a burning splinter to the mouth of the tube — it goes out with a “pop” sound, the test for hydrogen. This reaction is used for laboratory preparation of H2 gas. Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g) ↑

Yes — and this is a famous reaction known as the Thermite reaction. Aluminium is far more reactive than iron, and when a mixture of aluminium powder and iron(III) oxide is ignited, aluminium reduces iron oxide to molten iron with the release of enormous heat (about 850 kJ/mol). The molten iron formed is used to weld broken railway tracks and machinery on-site. Always demonstrate this with safety screens — the temperature crosses 2500 °C! 2 Al(s) + Fe2O3(s) → Al2O3(s) + 2 Fe(l) + Heat

No. Silver lies below copper in the activity series — it is less reactive than copper. Therefore, silver cannot displace copper from copper sulphate solution. If you dip a silver wire into blue CuSO4 solution, no reaction occurs and the blue colour stays unchanged. This is the reverse of question 6, which is why direction matters in displacement reactions. Ag(s) + CuSO4(aq) → No Reaction

Yes. Lead is placed slightly above copper in the activity series, so it is more reactive than copper. When a clean lead strip is placed in copper chloride solution, the bluish-green colour of the solution slowly fades and a reddish-brown deposit of copper appears on the lead surface. The lead dissolves as colourless lead chloride. The reaction is slow because the difference in reactivity between Pb and Cu is small. Pb(s) + CuCl2(aq) → PbCl2(aq) + Cu(s)

No, never. Gold sits at the very bottom of the activity series — it is the least reactive metal among common metals. To displace another metal, gold would need to be more reactive than that metal, but every other metal commonly studied is more reactive than gold. That is exactly why gold is called a noble metal and stays unreacted for centuries, making it ideal for jewellery and electrical contacts.