Zinc and Acid Reaction
Prepare hydrogen gas using zinc and dilute acids.
What this lesson covers
Why it matters
Granulated zinc meets dilute acid, and the test tube erupts in a storm of bubbles. You capture the invisible gas, and a burning splinter confirms its identity with a sharp pop.
The idea in plain words
Balance check: confirm the displacement of hydrogen by zinc.
Predict first
Why does zinc react with dilute acid to release gas?
Zinc sits above hydrogen in the reactivity series, allowing it to displace hydrogen from dilute acids.
- Zinc is more reactive than hydrogen — correct
- Acid is a liquid, so it always boils
- Zinc dissolves to form a blue solution
What you do
Add zinc to dilute acid. Observe the effervescence and collect the gas by downward displacement of water.
Check yourself
Which equation correctly represents the reaction of zinc with dilute hydrochloric acid?
Zinc displaces hydrogen from HCl to form zinc chloride and hydrogen gas: Zn + 2HCl → ZnCl₂ + H₂.
How do you confirm the gas collected is hydrogen?
Hydrogen is highly flammable; a burning splinter causes it to ignite rapidly with a characteristic 'pop'.
Why is downward displacement of water used to collect this gas?
Hydrogen is collected by downward displacement of water because it is insoluble (only sparingly soluble) in water.
- Zn + HCl → ZnCl + H
- Zn + 2HCl → ZnCl₂ + H₂ — correct
- Zn + H₂SO₄ → ZnSO₄ + H₂
- It turns lime water milky
- It relights a glowing splinter
- A burning splinter produces a 'pop' sound — correct
- Hydrogen is denser than air
- Hydrogen is insoluble in water — correct
- Hydrogen reacts with water to form acid