Acids & Bases – Interactive Study Tool

Nomenclature of Acids & Bases

How to name and write formulas for acids and bases

Click a compound to see its name built step by step.

HCl

3 rules to remember:
Binary acid (H + nonmetal): hydro___ic acid · Ternary acid (H + polyatomic with O): ___ic acid · Base (metal + OH⁻): ___ hydroxide. Exception: NH₃ = ammonia.

Oxyacid families — same central atom, different number of oxygens:
per___ic acid (one more O than the -ate) · ___ic acid (from the -ate ion) · ___ous acid (from the -ite ion, one less O) · hypo___ous acid (two less O than the -ate).
Chlorine set: HClO₄ perchloric · HClO₃ chloric · HClO₂ chlorous · HClO hypochlorous.

Acid nomenclature flow chart

Start: the formula begins with H (it’s an acid).

No oxygen (H + one nonmetal)
→ hydro + root + ic acid
HCl → hydrochloric acid

Contains oxygen (H + oxyanion)
name it from the polyatomic ion:
-ate → -ic acid
-ite → -ous acid

Extra / missing oxygens: one more O than the -ate → per…ic | two less O than the -ate → hypo…ous.

Bases: metal + OH⁻ → metal name + hydroxide. Exception: NH₃ = ammonia.

Everyday acids & bases — nomenclature in action

Binary Acid

Vinegar — acetic acid

CH₃COOH (acetic acid) is an organic acid — its H is written at the end. Vinegar is ~5% acetic acid in water. The sour taste is your tongue detecting H⁺ ions.

Base

Baking soda — sodium bicarbonate

NaHCO₃ is sodium hydrogen carbonate (baking soda). It's a weak base. Mixed with an acid (vinegar), it neutralizes to produce CO₂ — the bubbles that make baked goods rise!

Ternary Acid

Lemon juice — citric acid

Lemons contain citric acid (C₆H₈O₇), a triprotic acid that donates up to 3 H⁺ ions. pH ≈ 2–3. The sour taste you feel is classic acid behaviour — H⁺ ions reacting with your taste receptors.

Properties of Acids & Bases

Observable and chemical properties

Acids

● Sour taste (vinegar, lemons, citrus)
● Corrosive — harsh / burns skin
● React with active metals → H₂ gas (Zn + 2HCl → ZnCl₂ + H₂)
● React with carbonates / bicarbonates → CO₂ + H₂O + salt
● Neutralise bases → salt + water
● Turn blue litmus red; methyl orange red; leave phenolphthalein colourless
● pH < 7 · conduct electricity (electrolytes) · produce H⁺(aq) in water

Bases

● Bitter taste (baking soda, tonic water)
● Slippery / soapy feel (soap, bleach, drain cleaner)
● Caustic — dissolve organic matter (fats, skin, hair)
● Turn red litmus blue; phenolphthalein pink; methyl orange yellow
● Neutralise acids → salt + water
● React with ammonium salts → NH₃ gas · do not react with metals
● pH > 7 · conduct electricity (electrolytes) · produce OH⁻(aq) in water

Arrhenius definitions — ionization in water

Acid

HCl → H⁺(aq) + Cl⁻(aq)

Produces H⁺ ions in water

Base

NaOH → Na⁺(aq) + OH⁻(aq)

Produces OH⁻ ions in water

Ionization of Acids & Bases

Monoprotic vs polyprotic · strong vs weak dissociation

Pick an acid, then open the stopcock of ionization — watch each molecule dissociate and release its H⁺ ion(s).

Strength

TypeMonoprotic

H⁺ per molecule1

DissociationComplete

% ionized100%

Monoprotic acids (e.g. HCl) release one H⁺ per molecule. Polyprotic acids release more than one — H₂SO₄ is diprotic (2 H⁺), H₃PO₄ is triprotic (3 H⁺). Strong acids ionize completely; weak acids (like CH₃COOH) only partially ionize — an equilibrium.

Ionization in action

Triprotic Acid

Phosphoric acid in cola

Colas contain H₃PO₄ (phosphoric acid) for tartness — a triprotic acid that can release 3 H⁺ ions in three steps. It gives soft drinks a pH near 2.5, which is why soda is hard on tooth enamel.

The pH Scale

Power of Hydrogen — measuring acidity

Drag the slider to explore the pH of common substances.

pH value 7.0

pH7.0

NatureNeutral

[H⁺] relativeNeutral

ExamplePure water

pH formula: pH = −log[H⁺]. Each unit change = 10× difference in H⁺ concentration. pH 3 is 10× more acidic than pH 4, and 100× more acidic than pH 5.

Indicators & pH Testing

How we detect acids and bases

Set the pH and watch each indicator change colour.

Solution pH 7.0

Indicators are chemical substances that change colour at specific pH ranges. A good indicator has a sharp, clear colour transition. Red cabbage juice is a natural indicator — it contains anthocyanins that change from red (acid) through purple (neutral) to green/yellow (base).

Neutralization Reactions

Acid + Base → Salt + Water

Mix an acid and a base — watch the pH change as the reaction proceeds.

Acid (mL)50

Base (mL)50

Resulting pH7.0

SolutionNeutral

Example reaction:
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
acid + base → salt + water

Net ionic equation: H⁺(aq) + OH⁻(aq) → H₂O(l) — the spectator ions (Na⁺, Cl⁻) don't participate. This is always the net ionic equation for any strong acid + strong base neutralization.

Molecular · Ionic · Net-ionic (MIN)

Molecular equation

HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

Full ionic equation

H⁺(aq) + Cl⁻(aq) + Na⁺(aq) + OH⁻(aq) → Na⁺(aq) + Cl⁻(aq) + H₂O(l)

Net ionic equation

H⁺(aq) + OH⁻(aq) → H₂O(l)

Na⁺ and Cl⁻ appear unchanged on both sides — they are spectator ions and are removed.

A second example — H₂SO₄ + 2KOH

H₂SO₄(aq) + 2KOH(aq) → K₂SO₄(aq) + 2H₂O(l)

2H⁺(aq) + SO₄²⁻(aq) + 2K⁺(aq) + 2OH⁻(aq) → 2K⁺(aq) + SO₄²⁻(aq) + 2H₂O(l)

H⁺(aq) + OH⁻(aq) → H₂O(l)

Titration

Experimental neutralization — finding unknown concentration

Pick the reaction type, then hold the stopcock open to run titrant from the burette into the Erlenmeyer flask. Watch the phenolphthalein indicator change colour and the titration curve update live. SA = strong acid, WA = weak acid, SB = strong base, WB = weak base; the first term is what sits in the flask.

Reaction

Stopcock

NaOH added0.00 mL

Current pH1.00

StageBefore EP

IndicatorColourless

Lab apparatus

Titration curve (live)

Equivalence point (EP): moles of H⁺ = moles of OH⁻ — pH = 7 for strong/strong. End point: when the phenolphthalein turns pink and stays pink for 20 s. Formula: n = C × V → stoichiometry → find unknown concentration. Note: C₁V₁ = C₂V₂ is for dilutions only — NOT titrations!

Sources of Error — Equivalence Point vs End Point

The colour change (end point) should fall as close as possible to the true equivalence point — ideally a fraction of a drop before it. Watch the zoomed curve — a well-chosen indicator flips right where moles of H⁺ and OH⁻ match.

Strong acid + strong base has a long vertical jump through pH 7 — phenolphthalein, litmus and methyl orange all fall inside it. A weak acid + strong base jumps a shorter distance centred above pH 7, so only phenolphthalein sits in the jump.

1. Indicators are weak organic acids. Adding an indicator slightly increases the acidity of the flask, so a tiny bit of extra base is needed — a small systematic error present in every titration.
2. End point ≠ equivalence point. The equivalence point is where mol H⁺ = mol OH⁻ (true neutralization). The end point is where the indicator changes colour — with a good indicator, just before the equivalence point. A good indicator makes this volume difference negligible.

Neutralization & Titration Calculations

n = C · V → mole ratio → solve for the unknown

Set up an acid–base titration. The solver walks the mole bridge and finds the unknown concentration step by step.

Acid

[Acid] mol/L1.00

Acid vol (mL)25

Base (titrant)

Base

[Base] mol/L1.00

Balanced ratio (A : B)1 : 1

Base vol needed— mL

Balanced equation:
Method: (1) balance the equation, (2) n(known) = C × V, (3) multiply by the mole ratio, (4) solve C = n/V or V = n/C. Remember: use the coefficient ratio, not C₁V₁ = C₂V₂ — this is a reaction, not a dilution.

Where these calculations are used

Analytical chemistry

Standardization & quality control

Factories titrate to check concentration — vinegar acidity, vitamin-C in juice, acid in a battery. A standard solution of known concentration is titrated against the sample, and n = C·V plus the mole ratio gives the unknown exactly.

Periodic Table

Class-standard table · based on mass of carbon-12 = 12.00

Read molar masses off this table when converting between grams and moles in titration calculations.

Ion Chart

Class-standard chart · common cations, anions & polyatomic ions with their charges

Names, formulae, and charges of common ions — positive ions (cations) and negative ions (anions)

Use these charges to name acids and bases correctly and to write the salt produced by a neutralization reaction.

Real-World Applications

Acids and bases in everyday life

Acids in the body

Stomach acid (HCl)

Your stomach produces HCl at pH 1.5–3.5 — strong enough to dissolve metal. It denatures proteins and kills bacteria. Antacids (NaHCO₃, Mg(OH)₂) neutralize excess acid: HCl + NaHCO₃ → NaCl + H₂O + CO₂.

Environmental

Acid rain

SO₂ and NO₂ from factories dissolve in rainwater: SO₂ + H₂O → H₂SO₃ (sulfurous acid). Normal rain pH ≈ 5.6 (CO₂ dissolved); acid rain pH can drop to 4 or lower, damaging ecosystems and corroding buildings.

Bases in daily life

Soap & cleaning products

Soap is made by saponification — reacting fats with NaOH (a base). Household cleaners like bleach (NaOCl) and drain cleaner (NaOH) are all strongly basic. The slippery feel of bases is your skin cells being gently dissolved!

Biology

Blood pH buffering

Human blood is maintained at pH 7.35–7.45 by the carbonic acid buffer system: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. A drop to pH 7.0 (acidosis) or rise to 7.8 (alkalosis) is life-threatening.

Health

Tooth decay

Mouth bacteria produce acids (lactic acid, pH ~4.5) that dissolve tooth enamel (calcium phosphate). Toothpaste contains bases (fluoride compounds, CaCO₃) that neutralize mouth acids and re-harden enamel. Classic neutralization in your mouth!

Agriculture

Soil pH & farming

Most crops grow best at pH 6–7. Acidic soil (from acid rain or decomposition) is treated with lime (CaO or CaCO₃) to raise pH. Fertilizers can lower pH. Farmers test and adjust soil pH regularly — it's applied chemistry every season.

Acids & Bases Practice Quiz

25 questions · 20 seconds each · Speed bonus scoring

🧪

Ready to test your knowledge?

Covers nomenclature, properties, ionization, pH, indicators, neutralization, titration & calculations

25

Questions

20s

Per question

1000

Max points

Summary

Quick reference — acids & bases

Property	Acids	Bases
Taste	Sour	Bitter
Feel	Corrosive	Slippery
Litmus	Blue → Red	Red → Blue
pH	< 7	> 7
Ions produced	H⁺	OH⁻
Arrhenius definition	Produces H⁺ in water	Produces OH⁻ in water
Examples	HCl, H₂SO₄, HNO₃, CH₃COOH	NaOH, Ca(OH)₂, NH₃
Naming (binary)	hydro___ic acid	___ hydroxide
Naming (ternary)	___ic acid	(same rule)
Ionization	Mono- (HCl) / poly-protic (H₂SO₄ diprotic, H₃PO₄ triprotic)	Release OH⁻ (NaOH → Na⁺ + OH⁻)

Neutralization: Acid + Base → Salt + Water · Net ionic: H⁺ + OH⁻ → H₂O
Titration: n = C×V, then stoichiometry · Equivalence point ≠ End point (close but not always equal)
pH: 0–6 acid · 7 neutral · 8–14 base · Each unit = 10× change in [H⁺]

Acids & Bases — Interactive Study Tool