how will you reduce the following metals explain with a balanced chemical equation for each 1.metals of low reactivity 2.metals if high reactivity 3.metals if medium. reactivity
Answers
Extracting metals low in the reactivity series
Metals low in the reactivity series can be obtained by just heating.
For example, copper can be extracted from its sulphide ore by heating in the presence of air. This process is known as roasting. For example,
2Cu₂S + 6O₂ --------> 2Cu₂O + 2SO₂
2Cu₂O + Cu₂S --------> 6Cu + SO₂
Extracting metals middle in the reactivity series
The metals of middle reactivity are generally found as sulphide or carbonate ores.
If the ore is a carbonate ore, it is heated in the absence of air to form the metal oxide. This process is known as calcination. For example,
ZnCO₃ --------> ZnO + CO₂
If the ore is a sulphide ore, then it is heated in presence of air to get the metal oxide. This process is known as roasting. For example,
2ZnS + 3O₂ ---------> 2ZnO + 2SO₂
After obtaining the metal oxide, it is reduced using coke (carbon). This process is known as smelting. For example,
ZnO + C -------> Zn + CO
Sometimes, carbon monoxide is also used.
ZnO + CO ---------> Zn + CO₂
A metal of higher reactivity may also be used.
3ZnO + 2Al -----------> 3Zn + Al₂O₃
This reaction with iron oxide is used to join railway tracks and is highly exothermic and is known as thermit reaction.
Fe₂O₃ + 2Al --------> 2Fe + Al₂O₃
Extracting metals high up in the reactivity series
Such metals are obtained by electrolytic reduction.
For example,
NaCl
At anode:
2Cl⁻ -------> Cl₂ + 2e⁻
At cathode:
Na⁺ + e⁻ -----> Na