What is a Displacement Reaction?

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Grade Level:

Class 10

AI/ML, Physics, Biotechnology, Space Technology, Chemistry, Engineering, Medicine

Definition

What is it?

A displacement reaction is a chemical reaction where a more reactive element takes the place of a less reactive element in a compound. Think of it like a stronger player replacing a weaker player in a team. The more reactive element 'pushes out' the less reactive one.

Simple Example

Quick Example

Imagine your cricket team has a star batsman, Virat, and another good batsman, Rohit. If Rohit is already batting, but Virat is available and is a stronger player, the coach might send Virat in to bat instead of Rohit. Here, Virat (more reactive) displaces Rohit (less reactive) from the batting position (the compound).

Worked Example

Step-by-Step

Let's see what happens when we put an iron nail into a copper sulphate solution.

Step 1: Identify the reactants. We have Iron (Fe) and Copper Sulphate (CuSO4). In CuSO4, Copper (Cu) is bonded with Sulphate (SO4).
---Step 2: Compare the reactivity. Iron (Fe) is more reactive than Copper (Cu). You can check a reactivity series chart for this.
---Step 3: Since Iron is more reactive, it will displace Copper from the copper sulphate solution. Iron will take Copper's place.
---Step 4: The Iron will bond with Sulphate to form Iron Sulphate (FeSO4). Copper will be left alone as solid Copper metal.
---Step 5: Write the balanced chemical equation: Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s).
---Answer: Iron displaces copper, forming iron sulphate and solid copper.

Why It Matters

Understanding displacement reactions is crucial in fields like Chemistry and Metallurgy for extracting metals from their ores. It helps engineers design processes to prevent corrosion, like coating iron with zinc. Doctors also use principles of reactivity to understand how different elements interact in the body.

Common Mistakes

MISTAKE: Assuming any element can displace another. | CORRECTION: Only a more reactive element can displace a less reactive one. Always check the reactivity series.

MISTAKE: Forgetting to balance the chemical equation after writing the products. | CORRECTION: Always ensure the number of atoms of each element is the same on both sides of the reaction arrow.

MISTAKE: Confusing displacement with double displacement. | CORRECTION: In single displacement, one element replaces another. In double displacement, two compounds swap parts (like partners in a dance).

Practice Questions

Try It Yourself

QUESTION: What happens when Zinc (Zn) is added to a solution of Silver Nitrate (AgNO3)? (Hint: Zinc is more reactive than Silver) | ANSWER: Zinc displaces Silver, forming Zinc Nitrate (Zn(NO3)2) and solid Silver (Ag).

QUESTION: Can Copper (Cu) displace Iron (Fe) from Iron Sulphate (FeSO4) solution? Explain why or why not. | ANSWER: No, Copper cannot displace Iron from Iron Sulphate solution. This is because Copper is less reactive than Iron, and a less reactive element cannot displace a more reactive one.

QUESTION: A student observes that a shiny grey metal 'X' when dipped in a blue solution of 'YSulphate' turns the solution green and a reddish-brown solid 'Y' is formed. Identify metal 'X' and 'YSulphate' if 'X' is a common metal used in construction. Write the chemical equation. | ANSWER: Metal 'X' is Iron (Fe). 'YSulphate' is Copper Sulphate (CuSO4). The chemical equation is Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s).

MCQ

Quick Quiz

Which of the following reactions is a displacement reaction?

NaCl + AgNO3 → AgCl + NaNO3

2H2 + O2 → 2H2O

Zn + H2SO4 → ZnSO4 + H2

CaCO3 → CaO + CO2

The Correct Answer Is:

Option C shows Zinc (Zn) displacing Hydrogen (H) from Sulphuric Acid (H2SO4) because Zinc is more reactive than Hydrogen. Options A, B, and D are double displacement, combination, and decomposition reactions respectively.

Real World Connection

In the Real World

Displacement reactions are used in the process of galvanization, where iron objects (like water pipes or roofing sheets in India) are coated with a layer of zinc. Zinc is more reactive than iron, so if the coating gets scratched, the zinc reacts first with oxygen and moisture, protecting the iron underneath from rusting. This extends the life of many metal structures around us.

Key Vocabulary

Key Terms

REACTIVITY SERIES: A list of metals arranged in order of their decreasing reactivity. | COMPOUND: A substance formed when two or more chemical elements are chemically bonded together. | REACTANT: A substance that takes part in and undergoes change during a reaction. | PRODUCT: A substance that is formed as a result of a chemical reaction.

What's Next

What to Learn Next

Great job understanding displacement reactions! Next, you should explore 'Double Displacement Reactions'. This concept builds on what you've learned about reactivity and will show you how two compounds can swap their parts, leading to exciting new products.