Testing the Reactivity of Metals in Acid

GCSE Chemistry

The reactivity series is one of the most important ideas in GCSE Chemistry. It helps us predict which metals will react with acids, which ones will displace others, and how metals behave in real industrial and environmental processes. One of the simplest ways for students to explore the reactivity series is to react metals with dilute hydrochloric or sulfuric acid and observe what happens.

This practical gives clear, visible results and teaches students how to compare reactivity using real data.

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The Chemistry

More reactive metals react faster with acids, producing:

• a salt, and

• hydrogen gas.

For example:

$$\text{Mg (s) + 2HCl (aq) → MgCl}_2\text{ (aq) + H}_2\text{ (g)}$$

The rate of hydrogen gas release is a direct indicator of metal reactivity.

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The Experiment

Equipment:

• Metals in small pieces: magnesium, zinc, iron, copper

• Dilute hydrochloric acid (1–2 M)

• Test tubes

• Measuring cylinder

• Stopwatch

• Splint for the hydrogen pop test

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Method

1. Add 10 cm³ of dilute acid to each test tube.

2. Add equal-sized pieces of metal to each tube.

3. Observe:

   • speed of bubbling

   • temperature change

   • time taken for reaction to slow or stop

4. Record the time for visible reaction or measure the volume of gas produced over a set time for a quantitative comparison.

5. Perform the hydrogen pop test by bringing a lit splint near the mouth of the tube (after removing excess acid).

This shows which metals are more reactive.

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Typical Results

Metal	Reaction with Acid	Rate of Bubbles	Hydrogen Test	Reactivity Ranking
Magnesium	Vigorous, immediate fizzing, warm beaker	Very fast	Loud pop	Most reactive
Zinc	Steady fizzing, moderate heat	Medium	Clear pop	Reactive
Iron	Slow fizzing, slight warming	Slow	Weak pop	Less reactive
Copper	No visible reaction	None	No pop	Not reactive

This matches their positions in the reactivity series.

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Why It Works in Teaching

Students can see and hear the differences in reactivity within seconds. Magnesium reacts explosively compared to iron, and copper’s complete lack of reaction makes the trend unmistakable.

The experiment also helps link the reactivity series to:

• displacement reactions

• extraction of metals

• corrosion

• industrial processes

It’s visual, memorable, and entirely rooted in core chemistry.

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Skills Highlight

• Comparing reaction rates

• Using qualitative and quantitative observations

• Performing the hydrogen pop test

• Recording data in a table

• Ranking metals by observed reactivity

• Linking practical outcomes to the reactivity series