82 articles
Acids, Bases & Salts
pH, strong and weak acids, buffers, titrations, indicators and salt chemistry.
Titrating an Antacid Tablet
A back-titration practical to find how much acid an antacid tablet can neutralise and how much calcium carbonate it really contains, with method, sample results, full calculation, evaluation and extensions.
Industrial Bases: Sodium Hydroxide, Lime and Ammonia
The bases that keep industry running: sodium hydroxide, lime, ammonia, sodium carbonate and potassium hydroxide, with how each is made, the scale of production and their key uses from soap to steel.
The Blood Buffer: How Your Body Holds pH at 7.4
How the carbonic acid–hydrogencarbonate buffer, proteins and phosphate keep blood between pH 7.35 and 7.45, how lungs and kidneys help, and what goes wrong in acidosis and alkalosis.
Brønsted–Lowry Acids and Bases
Acids donate protons, bases accept them. A complete guide to the Brønsted–Lowry theory with conjugate pairs, amphoteric water, worked examples and practice questions.
How to Choose the Right Indicator for a Titration
A step-by-step method for picking an acid–base indicator: find the equivalence pH, match it to the indicator's colour-change range, and avoid the classic mistakes. Includes a reference table.
Common Weak Acids and Their pKa Values
A reference guide to 20 weak acids you'll meet in the lab, the kitchen and the body, with formulas, pKa values, where they occur, and what their strength means in practice.
How to Identify Conjugate Acid–Base Pairs
A reliable four-step method for finding conjugate acids and bases in any equation, how to write the conjugate of a given species, polyprotic ladders, and 20 practice questions with answers.
Measuring the Enthalpy of Neutralisation
A complete practical guide to measuring the enthalpy change when an acid neutralises an alkali: method, results table, extrapolation graph, calculation, why strong acids all give about −57 kJ/mol, and how to improve accuracy.
Equivalence Point vs End Point
The equivalence point is where reactants are in exact stoichiometric amounts; the end point is where you see the signal. How they differ, why they don't always match, and how to minimise the gap.
Hydrofluoric Acid: A 'Weak' Acid That's Extremely Dangerous
Why hydrofluoric acid is chemically a weak acid yet one of the most hazardous chemicals in industry: how it penetrates skin, attacks calcium, dissolves glass, and why it's used anyway.
Indicators and Titration Curves Practice
15 practice questions on acid–base indicators and titration curves: colours at given pH values, choosing indicators, reading curves, pKin and colour ratios, and double-indicator titrations, with explained answers.
Ka and pKa: Measuring Acid Strength
What the acid dissociation constant Ka and pKa tell you, how to convert between them, a table of common pKa values, and how pKa predicts buffers, indicators and reaction direction.
Kb and pKb Explained
What the base dissociation constant Kb and pKb measure, how to read them, why some bases are stronger than others, and the modern pKaH convention used in organic chemistry.
Kw: The Ionic Product of Water and Why Neutral Isn't Always pH 7
What Kw is, where the value 1.0 × 10⁻¹⁴ comes from, how it links [H⁺] and [OH⁻] in every solution, and why pure water's pH changes with temperature while staying neutral.
Methyl Orange as an Indicator
Methyl orange explained: its azo-dye structure, why it's red in acid and yellow in alkali, its pH 3.1–4.4 range, which titrations it suits, screened methyl orange, and practical tips.
Ocean pH: Past, Present and Future
How the ocean's carbonate system sets seawater pH near 8.1, how absorbing carbon dioxide is lowering it, why a 0.1 drop matters, and what ocean acidification means for shells, corals and the food web.
Soil pH and Plant Growth
Why soil pH controls which nutrients plants can absorb, how acidic and alkaline soils form, which plants prefer each, how to test soil and how lime and sulfur change pH, with the chemistry behind hydrangea colours.
pH Calculations Practice Problems with Answers
20 pH practice problems in rising difficulty: strong acids, strong bases, [H⁺] from pH, masses, dilution, mixing, weak acids and temperature, each with full worked solutions.
How a pH Meter Works
Inside the glass electrode: how a thin glass membrane turns hydrogen ion concentration into a voltage, the Nernst equation's 59 mV per pH unit, reference electrodes, calibration, temperature compensation and care.
pH Inside the Body: Stomach, Blood, Skin and More
A tour of pH around the human body, from the stomach at pH 1.5 to pancreatic juice at 8, why each fluid has the pH it does, how the body controls it, and what happens when it goes wrong.
Phenolphthalein: Why It Turns Pink
The structure and chemistry of phenolphthalein: why it's colourless in acid and pink in alkali, why the pink fades in very strong alkali, its uses in titrations and forensics, and its history.
pOH and pH: Converting Between Them
What pOH measures, why pH + pOH = 14 at 25 °C, how to move between pH, pOH, [H⁺] and [OH⁻], and how temperature changes the rule, with worked examples.
Teaching Titration Technique
A teacher's guide to titration: a lesson sequence from equipment skills to full titrations, common student errors and how to catch them, assessing practical skills, calculations scaffolding and differentiated tasks.
Common Titration Errors and How to Avoid Them
Fifteen common titration mistakes, from unrinsed burettes to overshooting the end point, with what each does to your titre and calculated concentration, and practical fixes for more accurate results.
Titration Practice Problems with Worked Answers
20 titration practice problems from basic 1:1 calculations to dilutions, back titrations, diprotic acids, percentage purity and water of crystallisation, each with a full step-by-step solution.
Finding the Acetic Acid Content of Vinegar
A classic titration practical: dilute vinegar accurately, titrate with standardised sodium hydroxide using phenolphthalein, and calculate its ethanoic acid concentration and percentage, with sample data and evaluation.
Strong vs. Weak Acids: What's the Difference?
Why 'strong' and 'concentrated' mean different things, the seven common strong acids, how Ka and pKa measure acid strength, and how to calculate the pH of a weak acid.
Arrhenius, Brønsted-Lowry and Lewis Acids and Bases Explained
The three definitions of acids and bases, what each one adds, conjugate acid-base pairs, amphoteric substances, and how to tell which definition a question wants.
What Makes an Acid Strong? Bond Strength, Polarity and Stability
Why some acids give up protons easily and others don't: bond strength, electronegativity, oxygen count in oxyacids, inductive effects, resonance and solvation, with ranking examples.
Amino Acids as Acids and Bases: Zwitterions and pI
How amino acids carry both acidic and basic groups, why they exist as zwitterions, how their charge changes with pH, how to calculate the isoelectric point, and why it matters for proteins and electrophoresis.