Question
Iron from a blast furnace is treated with oxygen and with calcium oxide to make steel.
Which substances in the iron are removed?
▶️Answer/Explanation
Ans: A
During the steelmaking process in a basic oxygen furnace (BOF) or oxygen converter, a controlled stream of pure oxygen is blown onto the molten iron. The oxygen reacts with the carbon in the iron to form carbon monoxide (CO) and carbon dioxide.
During the steelmaking process, the impurities present in the iron, such as silicon oxide , manganese oxide (MnO), and phosphorus oxide, are considered acidic impurities. Calcium oxide reacts with these acidic oxides to form slag, which is a molten mixture of various oxides.
Question
Four equations are shown.
1\( C + O_2 \rightarrow CO_2\)
2 \(CaCO_3 \rightarrow CaO + CO_2\)
3 \(SiO_2 + 2CO \rightarrow Si + 2CO_2\)
4 \(Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2\)
Which equations represent reactions that take place during the extraction of iron from hematite?
A 1, 2 and 3 B 1, 2 and 4 C 2, 3 and 4 D 3 and 4 only
▶️Answer/Explanation
Ans: B
In the blast furnace, carbon monoxide (CO) acts as the reducing agent. It reacts with hematite to produce elemental iron (Fe) and carbon dioxide. This is the main reduction reaction that yields iron in the form of molten metal.
In the blast furnace, coke (carbon) is used as a fuel to provide the heat required for the reduction process. It reacts with oxygen (from air blown into the furnace) to produce carbon dioxide as a byproduct.
In the blast furnace, calcium carbonate decomposes when heated, producing calcium oxide, commonly known as quicklime, and carbon dioxide gas. The calcium oxide then reacts with the acidic impurities in the iron ore, such as silica, to form calcium silicate, which constitutes the slag.
Question
Which statement about the extraction of metals is correct?
A Aluminium is extracted from the ore bauxite by electrolysis.
B Aluminium is extracted from the ore hematite by electrolysis.
C Iron is extracted from the ore bauxite by electrolysis.
D Iron is extracted from the ore hematite by electrolysis.
▶️Answer/Explanation
Ans: A
Aluminium is extracted from its ore, bauxite, through the process of electrolysis. Bauxite is the primary source of aluminium and is a mixture of various aluminium minerals, along with other impurities such as silica, iron oxides, titanium dioxide, and small amounts of other elements.
Question
Iron is extracted from its ore in a blast furnace. Hematite, coke, limestone and hot air are added to the furnace. Which explanation is not correct?
A. Coke burns and produces a high temperature.
B. Hematite is the ore containing the iron as iron(III) oxide.
C. Hot air provides the oxygen for the burning.
D. Limestone reduces the iron(III) oxide to iron.
▶️Answer/Explanation
Ans:
D
Limestone (calcium carbonate) is not used as a reducing agent to directly convert iron(III) oxide to iron (Fe). The reduction of iron(III) oxide to iron is typically carried out using carbon monoxide (CO) or hydrogen as the reducing agents in the blast furnace during the iron production process.
Question
Iron is extracted from its ore in a blast furnace.
The equations for four different reactions are shown.
- 4Fe + 3CO2 → 2Fe2O3 + 3C
- CO2 → C + O2
- CO2 + C → 2CO
- Fe2O3 + 3CO → 2Fe + 3CO2
Which equations represent reactions that occur in the blast furnace?
A 1 and 2 only B 1 and 3 only C 2 and 3 only D 3 and 4 only
▶️Answer/Explanation
Ans:
D
CO2 + C → 2CO
This equation represents the formation of carbon monoxide (CO) from carbon (C) and carbon dioxide. In the blast furnace, coke (carbon) is used as the source of carbon. When the carbon reacts with the carbon dioxide produced from other reactions, it forms carbon monoxide. The carbon monoxide is a crucial reducing agent that will reduce the iron(III) oxide to produce iron metal.
Fe2O3 + 3CO → 2Fe + 3CO2
This equation represents the reduction of iron(III) oxide with carbon monoxide (CO) as the reducing agent. In the blast furnace, carbon monoxide reacts with iron(III) oxide to produce elemental iron (Fe) and carbon dioxide. This reaction is a key step in the extraction of iron, as it results in the formation of molten iron that can be collected at the bottom of the furnace.