627 articles
All articles — Page 9
Every article in the chemistry library, newest first.
Buffer Practice Problems
15 buffer practice problems with full solutions: pH from concentrations, buffers made by partial neutralisation, designing a buffer for a target pH, adding acid and base, dilution, capacity and blood.
Burette vs Pipette
The difference between a burette and a pipette explained for beginners: what each measures, how they're read and used, typical uncertainties, volumetric vs graduated pipettes, why a titration needs both, common mistakes and how to choose the right one.
Calcium, Phosphate and Bone Chemistry
What bones and teeth are made of: hydroxyapatite and collagen, why bone is both strong and tough, constant remodelling by osteoblasts and osteoclasts, how hormones control blood calcium, tooth enamel and acid, fluoride, and osteoporosis.
How to Calculate pH from Concentration
Step-by-step pH calculations: strong acids, strong bases, converting pH back to [H⁺], dilutions, mixing an acid with a base, and the very dilute acid trap, with worked answers.
Calculating Percentage Uncertainty
How to find absolute and percentage uncertainty for balances, thermometers, pipettes and burettes, how to combine uncertainties in a calculation, and how to compare your result with an accepted value, with worked examples.
Making and Using a Calibration Curve
How to make a calibration curve to measure concentration: preparing standards by serial dilution, measuring a signal, plotting and fitting the line, reading off unknowns, linear range, blanks and checking reliability.
The Calvin Cycle
How plants turn CO₂ into sugar: the three phases of the Calvin cycle (fixation by RuBisCO, reduction, regeneration of RuBP), the ATP and NADPH budget, Calvin's carbon-14 experiments, RuBisCO's oxygen problem, photorespiration, and C4 and CAM plants.
Carbohydrates: Sugars, Starch and Fibre
A beginner's guide to carbohydrates: what they are chemically, monosaccharides, disaccharides and polysaccharides, how the body digests and uses them, fibre, glycaemic index, and common myths about sugar and starch.
Carbon Monoxide Poisoning: The Chemistry
Why carbon monoxide is so dangerous: how incomplete combustion makes it, why it binds haemoglobin's iron about 200–250 times more strongly than oxygen, the left-shifted oxygen curve, effects on cells, symptoms, treatment with oxygen and how CO detectors work.
The Cathode Ray Tube Experiment Explained
A beginner's guide to the cathode ray tube: how the tube is built, what happens when high voltage is applied, the observations that showed cathode rays are negatively charged particles, how electric and magnetic fields deflect the beam, how Thomson used it to discover the electron, and how the same technology powered old TVs and oscilloscopes.
Cellular Respiration: The Chemistry of Burning Glucose
Respiration as controlled combustion: the overall equation and its energy, why cells release energy in small steps, the four stages (glycolysis, link reaction, Krebs cycle, oxidative phosphorylation), redox and NAD⁺, the ATP yield and efficiency.
Chadwick and the Discovery of the Neutron
The story of James Chadwick's 1932 discovery of the neutron: a decade-long search, Chadwick's years in a German internment camp, the beryllium radiation puzzle, the Joliot-Curies' near miss, the ten days of experiments that settled it, how he calculated the neutron's mass, and how the discovery led to nuclear fission.
Chemical Storage and Incompatible Chemicals
Why chemicals can't simply be stored alphabetically: incompatible groups such as acids and bases, oxidisers and flammables, water-reactive metals and cyanides with acids; segregation by hazard class, flammables cabinets, labelling, shelf life, peroxide-forming solvents and stock control.
Digestion as Chemistry: Enzymes from Mouth to Gut
A chemist's journey through the digestive system: hydrolysis of carbohydrates, proteins and fats, the enzymes at each stage, stomach acid and pH changes, bile as an emulsifier, absorption, and the fermentation work of gut bacteria.
The Chemistry of Attraction: Oxytocin, Dopamine and More
What chemistry can and can't tell us about attraction and love: dopamine and reward, oxytocin and vasopressin in bonding (and what the prairie vole studies showed), sex hormones, stress chemistry, pheromone claims, and why 'love is just chemistry' oversimplifies.
How Painkillers Work
The chemistry of pain relief: how pain signals start, how aspirin and ibuprofen block COX enzymes and prostaglandins, the puzzle of paracetamol and its overdose chemistry, how opioids act on the body's own pain-control receptors, and how local anaesthetics block nerve signals.
The Chemistry of Sleep: Melatonin and Adenosine
Why you feel sleepy: the two-process model of sleep, adenosine building up from ATP use and caffeine blocking its receptors, melatonin made from serotonin in darkness, cortisol and the circadian clock, orexin, sleep medicines and why screens at night matter.
How We Smell: Odour Molecules and Receptors
The chemistry of smell: what makes a molecule volatile and odorous, how about 400 olfactory receptors combine to recognise thousands of smells, why mirror-image molecules can smell different, how thiols are detected at parts per billion, and smell's role in flavour.
The Chemistry of Taste: Sweet, Sour, Salty, Bitter and Umami
How taste works at the molecular level: taste buds and receptor cells, the five basic tastes and the receptors and ions behind each, why sweeteners are so potent, why bitter tastes warn us, the tongue-map myth, and how smell creates flavour.
Chlorophyll: Why Plants Are Green
The chemistry of chlorophyll: its porphyrin-like ring with a central magnesium ion, why it absorbs red and blue light and reflects green, chlorophyll a vs b, accessory pigments, what happens when light is absorbed, and autumn colours.
Cholesterol: The Chemistry of a Misunderstood Molecule
What cholesterol actually is: its steroid structure, why the body needs it for membranes, hormones, bile and vitamin D, how it travels in LDL and HDL, where it comes from, and what 'good' and 'bad' cholesterol really mean.
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.
Chromatography: Separating Mixtures by How They Move
The big idea behind every type of chromatography: stationary and mobile phases, partition and adsorption, why substances separate, and how paper, TLC, gas, liquid and column chromatography compare.
Chromatography Practice Questions
Eighteen chromatography practice questions with worked answers: Rf calculations, reading paper and TLC chromatograms, identifying food dyes and inks, choosing solvents, polarity and retention, and interpreting gas chromatograms and HPLC peaks, from beginner to exam level.
Cofactors and Coenzymes
The non-protein helpers enzymes need: metal-ion cofactors and their roles, organic coenzymes such as NAD⁺, FAD, coenzyme A and PLP, prosthetic groups vs cosubstrates, the vitamin connection, and what happens when they're missing.
Colorimetry: Measuring Concentration by Colour
A practical guide to colorimetry: how a colorimeter works, choosing a complementary filter, making standards, zeroing with a blank, plotting a calibration curve and finding an unknown concentration, with sample results.
Column Chromatography
How to purify compounds by column chromatography: choosing the stationary phase and eluent with TLC, packing the column, loading the sample, collecting and analysing fractions, flash chromatography and common problems.
The Common Ion Effect in Acid–Base Systems
How adding an ion that's already in an equilibrium suppresses a weak acid's or base's ionisation, with worked calculations, the link to buffers, and examples from drug absorption to water treatment.
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.
EDTA Titrations and Water Hardness
How EDTA forms stable 1:1 complexes with metal ions, why pH 10 buffers and Eriochrome Black T are used, a full method for measuring water hardness, worked calculations in mg/dm³ as CaCO₃, and other uses of complexometric titration.