627 articles
All articles — Page 13
Every article in the chemistry library, newest first.
Ka and pKa Practice Problems
15 practice problems on acid dissociation constants: converting Ka and pKa, ranking acid strength, finding Ka from pH, weak acid pH, percent ionisation, conjugate bases and species at a given pH, with worked answers.
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.
Kitchen Science: 10 Experiments with Household Items
Ten quick kitchen chemistry demonstrations that take about ten minutes each: a CO₂ balloon, plastic from milk, dancing raisins, pepper and soap, ice cream in a bag, shiny coins, a lemon battery, emulsions, starch detection and a colour-changing cabbage drink, each with the chemistry behind it.
The Krebs Cycle
The citric acid cycle step by step: the link reaction, the eight reactions of the cycle with carbon counts and products, where CO₂, NADH, FADH₂ and GTP come from, why it's a cycle, regulation, and its role as the hub of metabolism.
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.
Famous Lab Accidents and the Safety Lessons They Taught
Real laboratory accidents, from Robert Bunsen's arsenic explosion to modern university incidents with dimethylmercury, tert-butyllithium and scaled-up energetic compounds, told respectfully and each paired with the safety lesson that changed practice.
Chemistry Lab Equipment: Names and Uses
A guide to 40 common pieces of chemistry lab equipment, grouped by job: containers, measuring, heating, separating, holding and safety, with what each is for and tips on using it correctly.
Chemistry Lab Report: An Annotated Example
A complete example chemistry lab report on the effect of temperature on reaction rate (sodium thiosulfate and acid), with annotations explaining what makes each section strong and how it would be marked.
How to Write a Chemistry Lab Report
A section-by-section guide to writing a clear chemistry lab report: title, aim, hypothesis, method, results tables and graphs, analysis, evaluation and conclusion, with tips on scientific writing and common mistakes.
Lab Safety Myths
Thirteen common lab safety myths corrected: that gloves protect against everything, that dilute means safe, that you should neutralise an acid splash with a base, that water puts out every fire, that small quantities can't hurt you, and more, with the chemistry behind each correction.
Lab Safety Quiz with Explanations
A 20-question lab safety quiz for chemistry students covering eye protection, hazard symbols, heating, diluting acids, spills, fires, gas cylinders, waste and emergencies, with the correct answer and a clear explanation of the reason behind every rule.
Chemistry Lab Safety Rules Every Student Should Know
The essential rules for working safely in a school or college chemistry lab: what to wear, how to behave, handling chemicals and glassware, heating safely, emergencies and clean-up, with the reason behind each rule.
Why Lanthanide Electron Configurations Are So Irregular
An advanced look at the lanthanides' electron configurations: the 4f and 5d competition, which elements have a 5d electron and which don't, why europium and ytterbium favour 4f⁷ and 4f¹⁴, why the +3 oxidation state dominates, the lanthanide contraction and its consequences, and how 4f electrons give lanthanides their special light and magnetism.
Lewis Acids and Bases: Electron Pairs, Not Protons
The Lewis definition explained: acids accept electron pairs, bases donate them. Examples from BF₃ to metal ions, how to spot Lewis acids, and why this view matters in organic and inorganic chemistry.
Lewis Dot Symbols for Atoms and Ions
A step-by-step guide to drawing Lewis dot symbols for atoms and ions: counting valence electrons, placing the dots, showing ionic charges, and using the symbols to predict simple ionic and covalent formulas.
The Light-Dependent Reactions
The light-dependent reactions of photosynthesis in detail: photosystems II and I, water splitting at the manganese cluster, the Z-scheme and redox potentials, electron carriers, NADPH formation, proton gradients and ATP synthase, and cyclic electron flow.
Lipids: Fats, Oils, Phospholipids and Steroids
What lipids are and why they don't dissolve in water: triglycerides, fats vs oils, phospholipids and membranes, steroids, waxes, how the body digests and stores fat, energy content and the emulsion test.
Litmus Paper: How It Works
What litmus is made from, why it turns red in acid and blue in alkali, red vs blue vs neutral litmus paper, how to use it correctly, its limits, and the history of one of chemistry's oldest indicators.
Lock-and-Key vs Induced-Fit Models
Two models of how enzymes bind their substrates, compared side by side: Fischer's rigid lock-and-key and Koshland's flexible induced fit, the evidence for each, hexokinase as the classic example, and conformational selection.
Mass Defect and Nuclear Binding Energy Calculations
Worked examples calculating mass defect and nuclear binding energy with E = mc²: helium-4, carbon-12, iron-56 and uranium-235, binding energy per nucleon, converting between u, kg, J and MeV, energy released in fusion and fission, and why iron-56 is so stable.
Mass Number: How to Calculate Neutrons, Protons and Electrons
Worked examples on mass number: what A and Z mean, how to find the numbers of protons, neutrons and electrons in atoms, isotopes and ions, reading nuclide notation, why mass number is a whole number but relative atomic mass isn't, and common exam traps.
Mass Spectrometry: How It Works
How a mass spectrometer ionises, accelerates, separates and detects particles by mass-to-charge ratio, how to read a mass spectrum, calculating relative atomic mass, the molecular ion, fragmentation and real-world uses.
Reading Mass Spectra for Elements and Isotopes
Worked examples on mass spectra of elements: identifying isotopes, calculating relative atomic mass from percentages and relative intensities, finding unknown abundances, and interpreting diatomic molecules like Cl₂ and Br₂.
Averages and Anomalies in Lab Data
Worked examples on handling repeat results in chemistry: calculating the mean, median and mode, spotting anomalous results, when to exclude them, concordant titres, range as a measure of spread, and choosing sensible significant figures for an average.
Measuring Volume: Beakers, Cylinders, Pipettes and Burettes
How to choose and use volume-measuring equipment: accuracy of beakers, measuring cylinders, pipettes, burettes and volumetric flasks, reading the meniscus correctly, and calculating percentage uncertainty.
Melting Point Determination
A practical lab guide to measuring melting points with a capillary tube and melting point apparatus: preparing the sample, heating rates, reading the range, what a broad or low range tells you about purity, mixed melting points, calibration and common errors.
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.
Microscale Chemistry: Small Experiments, Big Learning
A teacher's guide to microscale chemistry: what it is, why it improves safety, cost, speed and learning, the basic kit (well plates, dropper bottles, plastic pipettes, Petri dishes), five classic microscale experiments, and practical tips for introducing it in your classroom.
Millikan's Oil Drop Experiment: Measuring the Charge of an Electron
The story and physics of Robert Millikan's oil drop experiment (1909–1913): why the electron's charge mattered, the apparatus, balancing electric and gravitational forces, how the whole-number pattern revealed the elementary charge, a worked example, the controversy over his data, and the experiment's legacy.
Dietary Minerals: Why Your Body Needs Metals
A list of the essential dietary minerals, grouped into major minerals and trace elements, with what each does chemically, good food sources and what happens when you get too little or too much, from calcium and sodium to iron, zinc, iodine and selenium.