Question

When steam is passed over red hot iron we get which of the following products?
A. Ferric hydroxide and hydrogen
B. Ferric oxide and hydrogen
C. Ferrous hydroxide and hydrogen
D. Ferrous oxide and hydrogen

Answer 1

Hint: As we know that water has three phases-solid, liquid and gas. The gaseous phase of water is known as steam. It is also known as water vapor. It has a large amount of heat in it. Thus the chemical formula of steam is \[{{{H}}_2}{{O}}\]. The reaction between iron and water occurs only when the iron is in red hot form and water in steam form.

Complete answer:
> Chemically, iron is ${{Fe}}$. It does not have the ability to react with water under normal temperatures.  Thus, it is given high temperatures. Thus the iron is heated strongly till it becomes red hot.
> Generally, alkali metals are reactive with water. The reaction is exothermic. It produces metal hydroxides and hydrogen molecules. But iron is not as reactive towards water as alkali metals. Thus it is provided with a large amount of heat. Usually, metals which have moderate reactivity react with steam to produce metal oxides and hydrogen gas. Therefore, iron produces iron oxide and hydrogen gas, when steam is passed over red hot iron.
The chemical reaction is given below:
${{3Fe}} + 4{{{H}}_2}{{O}}\xrightarrow{\Delta }{{F}}{{{e}}_3}{{{O}}_4} + 4{{{H}}_2}$
In the above reaction, iron gets oxidized to ferric oxide by accepting oxygen and water gets reduced to hydrogen by losing oxygen.
> Iron oxide formed is also known as magnetite.

Thus, the correct option is B.

Note: An important thing to note is that we should know about the reactivity series of metals. The reactivity series of metals is given below:
${{K}} > {{Na}} > {{Li}} > {{Ca}} > {{Mg}} > {{Zn}} > {{Fe}} > {{H}} > {{Cu}} > {{Au}}$. ${{K}}$, ${{Na}}$, ${{Li}}$ are alkali metals and ${{Ca}}$ and ${{Mg}}$ are alkaline earth metals.