Write balanced chemical equations to explain what happens, when(i) Mercuric oxide is heated.(ii) Mixture of cuprous oxide and cuprous sulphide is heated.(iii) Aluminium is reacted with manganese dioxide.(iv) Ferric oxide is reduced with aluminium.(v) Zinc carbonate undergoes calcination.


The balanced chemical equations are given below: 

(i) When mercuric oxide (HgO), a red solid, is heated at a very high temperature, it decomposes to give mercury (Hg), a grey residue and Oxygen gas (O₂) liberates.
$2HgO \xrightarrow{Heat} 2 Hg + O_2$

(ii) When a mixture of cuprous oxide and cuprous sulphide is heated,  copper metal is produced as residue along with the evolution of SO2 gas.
$2Cu_2O + 2Cu_2S \xrightarrow{Heat} 6Cu + SO_2$

(iii) When Aluminium is reacted with manganese dioxide, Aluminium oxide (Al2O3) and Manganese (Mn) is produced as a residue.
$3MnO_2 + 4 Al → 2Al_2O_3 + 3Mn +heat$

(iv) When Ferric oxide is reduced with aluminium, Aluminium oxide (Al2O3) and iron (Fe) is produced as a residue.
$Fe_2O_3 + 2Al → Al_2O-3 + 2Fe + heat$

(v) When Zinc carbonate undergoes calcination (heated in the absence of air), zinc oxide, ZnO (yellow when hot and white when cold) is formed as residue along with the evolution of CO2 gas.
$ZnCO_3  \xrightarrow{Heat} ZnO + CO_2$

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Updated on: 10-Oct-2022

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