Question

What is an alloy? Give two examples with their chemical composition.

Answer 1

Hint: An alloy is the material formed by combining the metal and or non metal with some other elements. The elements are chosen based on their desirable properties required in the new material formed. Some commonly used alloys are steel, brass, bronze etc.

Complete step by step answer:
For such a type of question, let us begin with the definition of alloy.
So, an alloy can be defined as the combination of metals and or non metals which are combined with one or more elements.
The alloys contain properties of all its combinations. It is an impure substance that has characteristics of metals and desirable properties of added elements.
In our daily life, we use many alloys. The biggest example is the silver which is alloy of iron and carbon. Here, iron is a transition metal and the carbon is the non-metal.
Some other examples are- red gold, white gold, sterling silver, silicon steel, brass etc.
Now, let us explain the two mostly used alloys.

1.) Steel :- Steel is an alloy consisting of the transition metal iron and a carbon which provide it non-metallic character. The presence of carbon increases its strength and makes it fracture resistance. The major portion of steel is iron while carbon is present in a few percent. Now, these days one more term is very common which is stainless steel. This steel is corrosion resistant. This contains 11% chromium in addition to iron and carbon. The presence of chromium makes it corrosion and oxidation resistant.
Composition: Iron, Carbon and chromium (in case of stainless steel).

2.) Brass :- The second most commonly used alloy is the brass. It is an alloy of copper and zinc. The composition of zinc and copper is variable in the alloy depending on the electrical and mechanical properties required. It is bright golden in appearance. So, it is used as decoration material. It has the property of low friction and corrosion resistant. It is used in door knobs, locks, gears, zippers and electricals plugs etc.
Composition: Zinc and Copper (mostly) but sometimes lead is added in trace proportion

Note: It must be noted that steel, stainless steel and silicon steel are all three different alloys. The steel is alloy of iron and carbon only. The stainless steel is its branch only where 11 % chromium is also added in addition to iron and carbon which forms the major part. The silicon steel is a totally different alloy consisting of iron and silicon. The carbon is not present in it.
One more thing is that one should not get confused with brass and bronze. Both are different alloys. Brass consists of copper and zinc while bronze consists of copper, tin and some other metals like aluminium, manganese etc.