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Chemistry - Metals

Grade 10IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Physical properties of metals include high melting/boiling points, malleability, ductility, and high electrical/thermal conductivity due to a lattice of positive ions in a 'sea' of delocalised electrons.

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The Reactivity Series ranks metals by their tendency to lose electrons and form positive ions: K>Na>Ca>Mg>Al>(C)>Zn>Fe>(H)>Cu>Ag>AuK > Na > Ca > Mg > Al > (C) > Zn > Fe > (H) > Cu > Ag > Au.

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Metals above hydrogen in the reactivity series react with acids (e.g., HClHCl) to produce a salt and hydrogen gas (H2H_2).

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Metals are extracted based on their reactivity: highly reactive metals (above Carbon) require electrolysis (e.g., AlAl from Bauxite), while less reactive metals are reduced by Carbon or Carbon Monoxide (e.g., FeFe in the Blast Furnace).

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Alloys are mixtures of a metal with other elements. They are harder than pure metals because atoms of different sizes disrupt the regular lattice, preventing layers from sliding over each other.

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Rusting of iron requires both oxygen (O2O_2) and water (H2OH_2O). It can be prevented via barrier methods, galvanising (coating with ZnZn), or sacrificial protection (using a more reactive metal).

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In the Blast Furnace, Coke (CC) reacts with oxygen to form CO2CO_2, which then reacts with more Coke to form the reducing agent COCO. Limestone (CaCO3CaCO_3) is added to remove sandy impurities (SiO2SiO_2) as slag (CaSiO3CaSiO_3).

📐Formulae

2M(s)+2H2O(l)→2MOH(aq)+H2(g)2M(s) + 2H_2O(l) \rightarrow 2MOH(aq) + H_2(g) (Metal + Water)

Fe2O3(s)+3CO(g)→2Fe(l)+3CO2(g)Fe_2O_3(s) + 3CO(g) \rightarrow 2Fe(l) + 3CO_2(g) (Reduction of Iron Ore)

C(s)+O2(g)→CO2(g)C(s) + O_2(g) \rightarrow CO_2(g) (Combustion of Coke)

CO2(g)+C(s)→2CO(g)CO_2(g) + C(s) \rightarrow 2CO(g) (Formation of Reducing Agent)

CaO(s)+SiO2(s)→CaSiO3(l)CaO(s) + SiO_2(s) \rightarrow CaSiO_3(l) (Slag Formation)

Al3++3e−→AlAl^{3+} + 3e^- \rightarrow Al (Reduction at Cathode - Aluminum)

2O2−→O2+4e−2O^{2-} \rightarrow O_2 + 4e^- (Oxidation at Anode - Aluminum)

4Fe(s)+3O2(g)+2xH2O(l)→2Fe2O3⋅xH2O(s)4Fe(s) + 3O_2(g) + 2xH_2O(l) \rightarrow 2Fe_2O_3 \cdot xH_2O(s) (Rusting)

💡Examples

Problem 1:

Explain why magnesium can displace copper from a solution of copper(II) sulfate and write the ionic equation.

Solution:

Mg(s)+Cu2+(aq)→Mg2+(aq)+Cu(s)Mg(s) + Cu^{2+}(aq) \rightarrow Mg^{2+}(aq) + Cu(s)

Explanation:

Magnesium is higher than copper in the reactivity series. This means magnesium is more reactive and has a greater tendency to lose electrons to form Mg2+Mg^{2+} ions. It reduces the Cu2+Cu^{2+} ions to metallic copper.

Problem 2:

During the electrolysis of molten aluminum oxide, the carbon anodes must be replaced periodically. Why?

Solution:

C(s)+O2(g)→CO2(g)C(s) + O_2(g) \rightarrow CO_2(g)

Explanation:

At the high operating temperature, the oxygen gas (O2O_2) produced at the anode reacts with the graphite (carbon) anodes to form carbon dioxide gas. This causes the anodes to burn away over time.

Problem 3:

Why is Brass (an alloy of CuCu and ZnZn) harder than pure Copper?

Solution:

The presence of ZnZn atoms disrupts the CuCu lattice.

Explanation:

In pure CuCu, atoms are of the same size and arranged in regular layers which slide easily. In brass, the different sized ZnZn atoms distort the regular arrangement, making it difficult for layers to slide over one another.

Metals - Revision Notes & Key Formulas | IGCSE Grade 10 Science