Question

Define an alloy. How is the alloy prepared? List two advantages of making alloys. Write the composition of stainless steel. Why is steel preferred over iron? List two reasons.

Answer 1

Hint: Metals in their pure state are very reactive and hence are mixed with different metals in some fixed proportion to enhance their mechanical, physical and chemical properties. This phenomenon of mixing metals is known as alloying.

Complete answer:
When a metal is combined with other metals or a metal combined with one or more elements, then the product formed is termed as alloy. In the composition of an alloy, the presence of at least one metal is mandatory. The alloys are prepared in following steps:
Melting a large amount of base metal.
Gradually add the other metals in a specific proportion and then solidify to room temperature to form an alloy.
Advantages of making an alloy:
-Metal alloys are stronger as compared to pure metals i.e., pure metals are generally soft, so when alloyed with other metals or elements, then its strength increases and it becomes a more durable compound.
-Metal alloys are more resistant to corrosion as compared to metals present in their pure state because pure metals are chemically reactive and get easily oxidized in the presence of air and moisture while alloys prevent corrosion.
-Stainless steel: Steel is an alloy of carbon and iron and stainless steel consists of $10.5\% $ chromium, about $1.2\% $ carbon and other alloying elements. Steel is always preferred over iron due to following properties:
-Iron gets easily corroded when it comes in contact with air and moisture to form rust whereas steel is corrosion resistant i.e., it prevents the material from being corroded.
As steel is lighter than iron so it is easy to handle.
Steel has the tendency to retain magnetism i.e., it has more retentivity as compared to iron.
Steel is widely used in automobiles as it reduces the overall mass and hence the fuel is less consumed.

Note:
It is important to note that the metal in which the other metal is added i.e., the primary metal is termed as base metal. It is also known as solvent or matrix because addition of other elements take place in the molten state of primary metal. The other metals which are added to form an alloy are known as secondary constituents of solute. Alloy can be categorized on the basis of the number of elements combined like binary alloy, ternary alloy, etc.