Strong vs Weak Acids: HCl vs Ethanoic
The arrow is everything. One is permanent. One changes its mind.
Two unlabelled bottles. Both are acids. Both dissolve metals. Both turn litmus red. But one is a one-way demolition ball — it smashes apart and never goes back. The other is a pendulum — constantly swinging between molecule and ions.
The crime scene clue? A single arrow symbol.
⚡ The Equation Animator
All molecules shatter. No going back. pH very low.
Only ~1% dissociate. The rest snap back together. pH higher.
🔬 The Molecule Highlighter — Which H Falls Off?
Click each hydrogen to test your prediction. Only ONE is acidic.
⚠️ Examiner Trap: Students write "one of the H atoms" — but which one?
CH₃COOH has 4 hydrogens total. Three are bonded to carbon (CH₃). One is bonded to oxygen (COOH). Only the O–H hydrogen is acidic!
🏹 Arrow Selector Challenge
Nitric Acid (HNO₃) — a strong acid. Complete the equation:
HNO₃(aq) [ ? ] H⁺(aq) + NO₃⁻(aq)
Carbonic Acid (H₂CO₃) — a weak acid. Complete the equation:
H₂CO₃(aq) [ ? ] H⁺(aq) + HCO₃⁻(aq)
🔧 Equation Builder — Build the Ethanoic Equation
Click "Next Step" to construct the dissociation equation piece by piece.
CH₃COOH(aq)|
Start with ethanoic acid molecule
📊 Head-to-Head Comparison
| Property | HCl (Strong) | CH₃COOH (Weak) |
|---|---|---|
| Dissociation | Complete (100%) | Partial (~1%) |
| Arrow type | → (one-way) | ⇌ (reversible) |
| pH (same conc.) | Lower (more H⁺) | Higher (less H⁺) |
| Conductivity | Higher | Lower |
| Rate with Mg | Faster | Slower |
| Equilibrium? | No | Yes |
The Golden Rule
Strong acid → fully dissociates → →
Weak acid → partially dissociates → ⇌
The arrow is not decoration. It is chemical proof.
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