Direct comparison
Mixture vs compound
A mixture combines substances physically in variable proportions; a compound joins elements chemically in a fixed proportion to form a new substance.
The step most authors miss
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Side-by-side comparison
| Dimension | Mixture | Compound |
|---|---|---|
| How parts are combined | Physically mixed, no chemical bonds. | Chemically bonded together. |
| Proportions | Variable — any ratio is possible. | Fixed and definite. |
| Properties of components | Each component keeps its own properties. | New properties, often unlike the elements. |
| How to separate | Physical methods (filtering, distilling, evaporating). | Chemical reactions only. |
| New substance formed? | No. | Yes. |
| Energy change on forming | Usually little or none. | Often a notable energy change. |
| Written as | No single formula. | A definite chemical formula (e.g. H₂O). |
| Example | Air, seawater, sand and salt, a salad. | Water, carbon dioxide, table salt, glucose. |
| Sub-types | Homogeneous (uniform) or heterogeneous (non-uniform). | Ionic or covalent, by bond type. |
A simple decision: bonded or just blended?
To tell a mixture from a compound, ask two questions. First, are the components chemically bonded, or merely blended? If they can be separated by a physical method such as filtering, evaporation or using a magnet, it is a mixture. Second, is the ratio fixed? A compound always has the same proportions — water is always two hydrogen to one oxygen — while a mixture can hold its parts in any proportion, like coffee made stronger or weaker. Bonding plus a fixed ratio means a compound; blending in variable amounts means a mixture.
Common questions
FAQ
Is salt water a mixture or a compound?+
Salt water is a mixture. Although table salt itself is a compound, when it dissolves in water it simply disperses without forming new chemical bonds to the water, and you can vary how much salt you add. You can recover the salt by evaporating the water — a physical separation. Because the parts are blended rather than chemically combined, salt water is a mixture.
Can you separate a compound the same way as a mixture?+
No. A mixture can be separated by physical means such as filtering, distillation or evaporation, because its components are not chemically bonded. A compound’s elements are held by chemical bonds, so separating them requires a chemical reaction — for example, electrolysis to split water into hydrogen and oxygen. This difference in how they separate is a reliable test.
What is the difference between a homogeneous and heterogeneous mixture?+
Both are mixtures, distinguished by uniformity. A homogeneous mixture, such as salt water or air, looks the same throughout and its components are evenly distributed. A heterogeneous mixture, such as a salad or sand in water, has visibly distinct parts that are unevenly distributed. Compounds, by contrast, are always uniform because their composition is fixed by chemical bonding.
Going deeper
