⚗️ The Demolition Crew
Acids are aggressive demolition crews. Drop them on a Metal and they kick out Hydrogen. Drop them on a Carbonate and they smash it into CO₂ + Water. Let's witness the mayhem.
🔬 Virtual Lab — The Split-Screen Experiment
Drop the reactants into each beaker. Watch what happens at macro and micro level.
Beaker A Observation
Waiting for reactant…
Beaker B Observation
Waiting for reactant…
🔭 The Zoom Effect — What Atoms Are Doing
Acid + Metal (Beaker A)
You see rapid effervescence. The metal surface bubbles vigorously. Gas rises and, if tested with a lighted splint → SQUEAKY POP.
Word equation: Acid + Metal → Salt + Hydrogen
Acid + Carbonate (Beaker B)
Marble chips fizz slowly. Larger, rolling bubbles of CO₂. Gas tested through limewater → turns milky.
Word equation: Acid + Carbonate → Salt + Water + CO₂
🧪 Gas Tester Station
Choose the correct test for each gas. Cambridge Paper 6 loves this!
Gas from Beaker A (Mg + HCl)
Which test do you apply?
Gas from Beaker B (CaCO₃ + HCl)
Which test do you apply?
🧩 General Equation Builder
Drag the word tiles into the correct slots. Build both general equations.
Equation 1: Acid + Metal
Equation 2: Acid + Carbonate
⚖️ Balanced Symbol Equations
Magnesium + Hydrochloric Acid
Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
Note: 2 HCl needed to provide 2 Cl⁻ for MgCl₂ and 2 H⁺ for H₂
Calcium Carbonate + Hydrochloric Acid
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)
The CO₃²⁻ ion is "smashed" by H⁺: CO₃²⁻ + 2H⁺ → H₂O + CO₂
⚠️ Cambridge Examiner Traps
Trap 1: "All metals react with acid"
FALSE. Copper, silver, gold — unreactive with dilute HCl or H₂SO₄. Only metals above H in reactivity series react.
Trap 2: "Effervescence proves hydrogen"
FALSE. Effervescence just means gas is produced. You MUST test with a lighted splint for the squeaky pop to confirm H₂.
Trap 3: "CO₂ turns limewater blue"
FALSE. CO₂ turns limewater milky/cloudy (white precipitate of CaCO₃ forms). It does not change colour to blue!
Trap 4: Salt naming
HCl → chloride salts. H₂SO₄ → sulfate salts. HNO₃ → nitrate salts. Don't mix them up!
HAZARD WARNING — Dilute HCl
Dilute hydrochloric acid is corrosive. Wear safety goggles and gloves. If skin contact occurs, rinse with plenty of water. H₂ gas is flammable — ensure no naked flames near open containers when testing.
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