Key Differences
| Feature | Compound | Mixture |
|---|---|---|
| Formation | Formed by a chemical reaction (atoms combine in a fixed ratio) | Formed by physically combining substances |
| Composition | Fixed and definite | Variable; components can be in any ratio |
| Properties | Properties are different from the original components | Properties are similar to the original components |
| Separation | Can only be separated by chemical means (e.g., electrolysis) | Can be separated by physical means (e.g., filtration, evaporation) |
| Example | Water (H₂O), salt (NaCl) | Sand and water, air |
Explanations
* Chemical vs. Physical Change: Compounds are formed by a chemical change, where the original substances lose their identities and new substances with different properties are created. Mixtures are formed by a physical change, where the original substances retain their identities and can be separated back out.
* Fixed Ratio: Compounds always have a fixed ratio of elements by mass. For example, water is always two hydrogen atoms for every oxygen atom. Mixtures can have varying ratios of components.
* Properties: Compounds have unique properties distinct from their constituent elements. For example, water (H₂O) is a liquid at room temperature, while hydrogen and oxygen are gases. Mixtures retain the properties of their components. For example, sand in water will still have the properties of sand and water.
* Separation: Compounds require chemical reactions to be separated into their elements. Mixtures can be separated by physical methods like filtration, evaporation, or distillation.
Examples
* Compound: Salt (NaCl) is a compound because it's formed by a chemical reaction between sodium (Na) and chlorine (Cl). Salt has properties distinct from sodium and chlorine, and it can only be separated back into its elements by electrolysis.
* Mixture: Sand and water is a mixture because the sand and water are physically combined and retain their individual properties. You can easily separate them by letting the sand settle and then decanting (pouring off) the water.
In Summary
The key difference between compounds and mixtures lies in the way they are formed and their properties. Compounds are formed by chemical reactions, have fixed compositions, and unique properties. Mixtures are formed by physically combining substances, have variable compositions, and retain the properties of their components.
