Chemistry examples
Lists of real-world examples that make chemistry ideas easier to understand, from chemical and physical changes to compounds, mixtures, alloys and solvents. Each list explains the concept, shows how to recognize it and gives a short reason why every example fits.
Examples of chemical changes
A chemical change, or chemical reaction, turns one or more substances into new substances with different properties. Signs that one has happened include a color change, gas bubbles, a new smell, light, a temperature change or a solid forming in a liquid. Chemical changes are usually hard to reverse, unlike physical changes.
20 examplesExamples of compounds
A compound is a substance made of two or more elements chemically bonded in a fixed ratio, which its chemical formula shows. Compounds have properties that differ from those of their elements and can only be split into those elements by chemical reactions. Here are common compounds you meet at home, in your body and in the lab.
25 examplesExamples of mixtures
A mixture contains two or more substances that are physically combined but not chemically bonded, so each keeps its own properties. The proportions can vary, and the parts can usually be separated by physical methods such as filtering, evaporating or using a magnet. Most things in daily life, from the air you breathe to the food you eat, are mixtures.
20 examplesExamples of alloys
An alloy is a mixture of a metal with one or more other elements, usually other metals but sometimes nonmetals such as carbon. Alloys are usually made by melting the ingredients together, and they tend to be harder, stronger or more resistant to corrosion than the pure metals they contain. Here are common alloys and what they are made of.
12 examplesExamples of polar solvents
A polar solvent is made of molecules with an uneven distribution of charge, giving each molecule a slightly positive end and a slightly negative end. Polar solvents dissolve ionic and polar substances well, following the rule like dissolves like. Polarity is often compared using the dielectric constant (higher means more polar) and the dipole moment in debyes (D); the values below are approximate, near room temperature.
12 examplesSpontaneous endothermic processes
An endothermic process absorbs heat from its surroundings, so the surroundings get colder. Most processes that happen on their own release heat, but the ones below are spontaneous at room temperature and normal pressure even though they absorb heat, because they greatly increase entropy (disorder). The list includes chemical reactions as well as physical processes such as melting, evaporating and dissolving, and each item says which it is.
10 examplesExamples of physical changes
A physical change alters the form, size, shape or state of a substance without turning it into a new substance. Melting, freezing, boiling, dissolving, cutting and bending are all physical changes. The chemical composition stays the same, and many physical changes can be reversed.
20 examplesHomogeneous and heterogeneous mixtures
A homogeneous mixture has the same composition all the way through, so you cannot see its separate parts; it is also called a solution. A heterogeneous mixture is uneven, with parts you can see or that settle out over time. A quick test: if samples taken from different spots could look or behave differently, the mixture is heterogeneous.
20 examples