⚗️ Acids
Science › Chapter 10 › Acid
pH < 7
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Acid Simulation — Add HCl to Water

Click "Add Drop" to drip hydrochloric acid and see H⁺ ions form

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H₂O + HCl
01234567891011121314
7.0Starting pH — neutral water
Neutral — Green (Litmus)
Ready! Add drops of HCl to the water. Watch H⁺ ions appear and the pH fall below 7.
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Acid Properties & Examples

😝
Sour Taste
H⁺ ions stimulate sour taste receptors. Citric acid in lemons, lactic acid in yoghurt.
🔵→🔴
Turns Litmus Red
Blue litmus paper turns red in the presence of any acid — a key lab test.
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Conducts Electricity
H⁺ ions carry charge through water, making acid solutions good conductors.
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Reacts with Metals
HCl + Zn → ZnCl₂ + H₂↑. Acids corrode metals and release hydrogen gas.
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Citric Acid
Found in citrus fruits. pH ~2–3. Food preservative and flavouring agent.
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Sulphuric Acid H₂SO₄
Used in car batteries, fertiliser manufacture, and chemical industry. pH ~0.
🐜
Formic Acid
Injected by ants and bee stings. Causes burning sensation on skin.
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Acetic Acid CH₃COOH
Main component of vinegar. Weak acid — pH ~3. Used in cooking & preservation.
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Base Simulation — Add NaOH to Water

Click "Add Drop" to drip sodium hydroxide and see OH⁻ ions form

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H₂O + NaOH
01234567891011121314
7.0Starting pH — neutral water
Neutral — Green (Litmus)
Ready! Add drops of NaOH to water. Watch OH⁻ ions appear and the pH rise above 7.
📋

Base Properties & Examples

😬
Bitter Taste
Bases taste bitter — like baking soda. Never taste unknowns in the lab!
🤲
Slippery Feel
OH⁻ ions saponify skin oils, creating the slippery sensation of soap or bleach.
🔴→🔵
Turns Litmus Blue
Red litmus paper turns blue in any base — opposite of acids.
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pH Above 7
Strong bases like NaOH reach pH 13–14. Weak bases (ammonia) are pH 10–11.
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Sodium Hydroxide NaOH
Used to make soap and paper. Extremely corrosive at high concentrations.
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Magnesium Hydroxide
Mg(OH)₂ — "milk of magnesia". Neutralises excess stomach acid as an antacid.
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Calcium Hydroxide
Ca(OH)₂ — "lime". Added to acidic soil to raise pH and improve crop growth.
🦷
Toothpaste
Slightly basic (pH ~8) — neutralises acids produced by bacteria in the mouth.
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Neutralization Reaction — Step by Step

Drop acid, then base into the beakers — then combine them to see salt form and sediment

1 Drop Acid
2 Drop Base
3 Combine
4 Salt Forms
Waiting for reaction to begin…
HCl
NaOH
Result Beaker
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NaCl crystals
Result Beaker
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7.0 ✅ Neutral — acid and base have cancelled each other out!
pH 7 — Neutral solution (NaCl dissolved in water)
Step 1: Click "Add HCl" to drop acid into the left beaker. Watch H⁺ ions appear.
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What is Salt?

Salts are ionic compounds formed when an acid reacts with a base

Acid + Base → Salt + Water
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Table Salt — NaCl
HCl + NaOH → NaCl + H₂O. Used to season food and preserve meat.
🧁
Baking Soda — NaHCO₃
Releases CO₂ when heated, making dough rise. Also used as an antacid.
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Gypsum — CaSO₄
H₂SO₄ + Ca(OH)₂ → CaSO₄ + H₂O. Used in plaster of Paris and construction.
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Ammonium Nitrate — NH₄NO₃
HNO₃ + NH₃ → NH₄NO₃. Used as nitrogen fertiliser in agriculture.
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Medicine
Saline (NaCl solution) used in IV drips. Many drugs delivered as salt compounds.
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Properties of Salts
Crystalline solids. High melting points. Conduct electricity when dissolved.
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Washing Soda — Na₂CO₃
Used in glass-making, softening hard water, and textile processing.
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Exothermic Reaction
Neutralization releases heat — the beaker warms as acid and base combine.