In the previous lesson we came to know about the reactivity series in detail. Today we will go through how the reactivity series is useful in displacement reactions. First, what is a displacement reaction?
Displacement reaction is a chemical reaction in which a more reactive metal displaces (pushes out) the less reactive metal from the compound. For example:
Iron + copper sulfate ------- iron sulfate + copper
In this reaction iron is a more reactive metal than copper. Iron displaced or pushed out the less reactive metal copper from the compound, copper sulfate and then took it place forming iron sulfate.
In this picture iron nail is placed in a solution of copper sulfate. After the reaction iron sulfate solution is formed and the brown colored nail is copper metal on iron.
Now how is reactivity series used in these reactions?
From the reactivity series we are able to understand which metal is more reactive than the other metal. For example in the above reaction between iron and copper sulfate, we will go through the reactivity series in order to find whether iron is more reactive than copper or not.
Now if a reaction happens between copper and iron sulfate, will the displacement reaction take place? The answer is NO, because copper is a less reactive metal than iron and it is not capable of displacing iron from iron oxide. Hence, no reaction will take place.
Displacement Reactions Applications:
How are displacement reactions useful in our daily life? There are 2 main application of the displacement reactions in our daily routine.
Thermite Reaction: This reaction is used in the railway companies to weld rails together. This reaction includes the chemical reaction between aluminum and iron oxide, aluminum will displace iron from iron oxide and will form aluminum oxide, when heated, because it is more reactive than iron. The equation is as followed:
aluminum + iron oxide -------(on heating)-------- aluminum oxide + iron
This reaction releases a lot of energy. The temperature gets so high that the iron that is produced is molten (in liquid state). The iron oxide and aluminum powder react in a container placed on the rails. The molten iron produced in the reaction is shaped and cooled down to join the rails together.
In order for the reaction to take place, the iron oxide and aluminum mixture has to be heated. This is done using another reaction, this time between magnesium powder and barium nitrate. This reaction provides energy to start the reaction between aluminum and iron oxide.
2. Blast Furnace:
Carbon is not a metal, but it can be used to displace some metals from their compounds. Carbon will displace zinc, iron, tin and lead from their ores. An ore is a rock that contains a metal compound.
When iron ore is heated with carbon at very high temperatures, produces molten iron. Word equation for this reaction is:
Iron oxide + carbon ----(heated at high temperatures)----- iron+ carbon dioxide
This displacement reaction is carried out on a large scale, in a blast furnace.
Through this method we are able to obtain molten iron.
All pictures are taken from google.
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