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Activity 3.8 — Metals with Dilute Acids
NCERT Activity 3.8: Add dilute HCl to zinc, magnesium, iron, and copper separately. Observe the different rates of H₂ release (effervescence). Copper shows NO reaction. Confirm H₂ with the pop test.
How To Perform
1
Add HCl to Zinc
Moderate effervescence — Zn + 2HCl → ZnCl₂ + H₂↑
2
Add HCl to Magnesium
Vigorous effervescence, tube feels warm — Mg + 2HCl → MgCl₂ + H₂↑
3
Add HCl to Iron
Slow effervescence, greenish solution — Fe + 2HCl → FeCl₂ + H₂↑
4
Add HCl to Copper
No reaction — Cu is below hydrogen in the reactivity series
5
Pop Test
Burning matchstick at tube mouth → 'POP' confirms H₂
6
Conclude
Reactivity order: Mg > Zn > Fe > [H] > Cu
⚠️ Safety Notes
- •Dilute HCl is corrosive — wear safety goggles and avoid skin contact.
- •The pop test should be performed carefully — keep face away from the test tube mouth.
- •Hydrogen gas is flammable — do not produce large quantities near open flames.