Single Displacement Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Single Displacement.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

A reaction in which a more reactive element replaces a less reactive element in a compound.

A bully element kicks a weaker one out of its compound — like a stronger player replacing a weaker one on a team.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Pattern: A + BC → AC + B. The activity series predicts which element can replace which.

Common stuck point: The reaction only occurs if the free element is more reactive than the one in the compound. Check the activity series.

Worked Examples

Example 1

easy
Write the balanced equation for zinc metal reacting with hydrochloric acid.

Solution

  1. 1
    Single displacement: a more reactive element replaces a less reactive one: \text{A} + \text{BC} \rightarrow \text{AC} + \text{B}.
  2. 2
    Zinc displaces hydrogen: \text{Zn} + \text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 (unbalanced).
  3. 3
    Balanced: \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2. Check: Zn 1=1, H 2=2, Cl 2=2. ✓

Answer

\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2
In single displacement reactions, the activity series predicts whether the reaction will occur. Zinc is above hydrogen in the series, so it can displace hydrogen from the acid.

Example 2

medium
Will copper react with silver nitrate solution? If so, write the balanced equation. (Activity series: Cu is above Ag.)

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
Will gold (Au) react with \text{CuSO}_4 solution? (Au is below Cu in the activity series.)

Example 2

hard
Zinc metal is placed in a copper(II) sulfate solution (\text{CuSO}_4). The solution gradually loses its blue color and a reddish deposit forms. Write the balanced equation and explain what the color changes indicate.
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Background Knowledge

These ideas may be useful before you work through the harder examples.

chemical reaction