Question

Three common ores of iron are FeO, Fe2O3, and Fe3O4. Iron ores are often reduced to elemental iron by heating in the presence of carbon monoxide. These iron ores are all brittle and do not conduct electricity in their solid form.

a. Identify the oxidation number of the iron atoms in each of the three ores.

b. Choose one of the iron ores and write a balanced chemical equation to show its reduction reaction with carbon monoxide.

c. Considering the types of bonding involved, how and why do the properties of the ores differ from those of pure iron?

Carbon steel is an interstitial alloy of iron with a small amount of carbon which has greater strength and density than pure iron but maintains the metallic properties of iron.

d. Is the combination of iron with carbon to form steel a chemical or physical change? Explain your answer.

e. Draw a representation of the structure of this alloy.

f. As the percent carbon increases in steel, the ductility of the steel decreases. Explain why this might occur.

Answer 1

(a)

Oxidation number of iron :

FeO = +2

Fe2O3= +3

Fe3O4 = +2 and +3 since Fe3O4 is the mixture of FeO and Fe2O3.

(b) FeO + CO ----> Fe (s) + CO2

(c) In a pure iron metallic bond is exist between the particles of Fe. But in the form of ore metals forms ionic bond with the non-metals.

Hence the properties vary.

Yes carbon steel has greater strength than that of pure iron but retains the property of iron because no chemical reaction occurs between carbon and iron.

d)

Mixing of carbon in iron is a type of physical change since there is no chemical reactions occur between the carbon and iron. Carbon atoms diffuses in the place between the iron atoms.

(f) One of the property of non-metals are brittleness. It is non ductile .

So when the percentage of carbon increases its atoms also occupying more and more free places.

And increasing the brittleness. So the iron becomes less ductile.