Displacement reaction
Definition - Displacement means a change in position from one place to another. And displacement reaction is a chemical reaction where one element replaces another element in a compound.
Example:
Iron + Copper sulfate → Iron sulfate + Copper
What happens:
Iron (Fe) goes into the solution.
Copper (Cu) comes out.
So iron replaces copper. That is why it is called a displacement reaction, because an element displaces the other.
How does an element displace the other? In copper sulfate:
• copper is joined with sulfate.
When iron is added, iron forms a stronger chemical connection with sulfate than copper does.
So sulfate “switches element”:
• it leaves copper
• joins iron instead
• That leaves copper alone.
So:
Iron + Copper sulfate → Iron sulfate + Copper
Why does an element displace the other?
Atoms tend to move toward a more stable, lower-energy state.
In this reaction:
iron with sulfate is more stable than copper with sulfate
so the reaction naturally shifts to that arrangement
Since iron is more reactive than copper, the iron sulfate arrangement is energetically more favourable.
How fast does the reaction happen?
The speed of a displacement reaction changes because reactions depend on how easily particles can meet and react.
Factors affecting speed:
1. Type of substances:
• Some elements are much more reactive than others.
• More reactive elements displace other elements faster.
2. Temperature:
• Higher temperature makes particles move faster.
• Faster-moving particles collide more often, so the reaction speeds up.
3. Concentration:
• If a solution has more particles packed into it, collisions happen more frequently.
• More collisions usually make the reaction faster.
4. Surface area:
• Smaller pieces expose more area to the reaction.
• More exposed area means more particles can react at the same time.
A reaction is fast when effective collisions happen quickly and often.
It is slow when collisions happen less often or react less easily.
Fast displacement reaction:
Example:
Magnesium + copper sulfate
Magnesium + Copper sulfate → Magnesium sulfate + Copper
Slow displacement reaction:
Slow displacement reaction:
Example:
Iron + copper sulfate
Iron + Copper sulfate → Iron sulfate + Copper