How is 4FeS2 + 11O2 = 2Fe2O3 +8SO2 a single replacement reaction?
I don't think it is.
Single replacement reactions are the type AX + Y = YX + A
The reaction above is AX + Y = AY + YX
The reaction 4FeS2 + 11O2 = 2Fe2O3 + 8SO2 is actually a combination of two types of reactions: a combustion reaction and a synthesis reaction.
In this reaction, iron pyrite (FeS2) reacts with oxygen (O2) to form iron(III) oxide (Fe2O3) and sulfur dioxide (SO2).
The combustion reaction occurs when the iron pyrite and oxygen react, generating heat and light energy. This combustion reaction is represented by the equation:
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
The synthesis reaction takes place simultaneously, as the products of the combustion reaction combine to form iron(III) oxide and sulfur dioxide. This synthesis reaction is represented by the equation:
2Fe2O3 + 8SO2
Therefore, this equation is not a single replacement reaction, but a combination of a combustion reaction and a synthesis reaction.
The equation you provided, 4FeS2 + 11O2 = 2Fe2O3 + 8SO2, does not represent a single replacement reaction. It is actually a balanced chemical equation for a combustion reaction.
In a single replacement reaction, one element replaces another element in a compound. This type of reaction involves a chemical species breaking into its constituent elements, with one element replacing another in a new compound.
To identify a single replacement reaction, you should observe a reactant being replaced by another element in the product. An example of a single replacement reaction would be:
A + BC = B + AC
In the equation you provided, there is no element that is replacing another element in a compound. Instead, the equation represents the combustion of iron pyrite (FeS2) with oxygen (O2) to produce iron(III) oxide (Fe2O3) and sulfur dioxide (SO2).