Maharashtra State Board · Class 10 · Chemistry · Chapter 8

Metallurgy — Metals and Non-metals — Formula Sheet

Board Formulas

12 formulas

1.Reactivity Series (Descending)★
$K > N a > C a > M g > A l > Z n > F e > P b > H > C u > H g > A g > A u$
Above H → displaces H from acid. Below H → does not react with dilute HCl/H_2SO_4.
2.Formation of Ionic Bond
$N a + C l \to N a^{+} + C l^{-} \to N a C l$
Metal loses e-, non-metal gains e-, ions attract electrostatically.
3.Metal + Oxygen
$4 N a + O_{2} \to 2 N a_{2} O$
Metals form basic oxides. Na burns vigorously; Fe rusts slowly.
4.Metal + Acid★
$Metal + 2 H C l \to Metal chloride + H_{2} ↑$
Only metals above H in the activity series react. Cu, Ag, Au do not.
5.Metal Displacement in Solution
$F e + C u S O_{4} \to F e S O_{4} + C u$
Blue colour of CuSO_4 fades, brown Cu deposits on iron nail (Fe > Cu).
6.Roasting (Sulphide Ore)★
$2 Z n S + 3 O_{2} Δ 2 Z n O + 2 S O_{2}$
Sulphide ore heated in EXCESS air → metal oxide + SO_2. Used for Zn, Cu, Pb ores.
7.Calcination (Carbonate Ore)
$Z n C O_{3} Δ Z n O + C O_{2}$
Carbonate ore heated in LIMITED air → metal oxide + CO_2. Used for calamine, malachite.
8.Reduction of Oxide by Carbon
$Z n O + C Δ Z n + C O$
Middle-of-series metals (Zn, Fe, Pb) — cheap carbon reduction from coke.
9.Electrolytic Reduction (for K, Na, Ca, Mg, Al)
$At cathode: M^{n +} + n e^{-} \to M$
Molten metal chloride/oxide is electrolysed. Al from molten Al_2O_3 in cryolite (Hall-Héroult).
10.Rusting of Iron
$4 F e + 3 O_{2} + x H_{2} O \to 2 F e_{2} O_{3} \cdot x H_{2} O$
Both O_2 and H_2O required. Prevented by galvanising, painting, oiling, alloying.
11.Amphoteric Oxide (Al_2O_3)
$A l_{2} O_{3} + 6 H C l \to 2 A l C l_{3} + 3 H_{2} O; A l_{2} O_{3} + 2 N a O H \to 2 N a A l O_{2} + H_{2} O$
Reacts with both acid and base — the definition of amphoteric. Also true for ZnO.
12.Thermite Reaction★
$F e_{2} O_{3} + 2 A l \to 2 F e + A l_{2} O_{3} + heat$
Highly exothermic; molten iron used to weld broken railway tracks.