Heterogeneous
Definition and meaning of Heterogeneous in chemistry.
Heterogeneous describes a mixture or system whose composition is not uniform, containing two or more visibly or physically distinct phases or regions with different properties.
In more detail
In a heterogeneous mixture, the components remain physically separate rather than blending into a single uniform phase, so a sample taken from one spot can differ in composition from a sample taken elsewhere. The distinct regions are typically separable by physical means such as filtration, decanting, or settling. The term also applies to reactions and catalysis: a heterogeneous reaction involves reactants in different phases (e.g., a solid catalyst acting on gaseous or liquid reactants), which is important industrially because the catalyst can be easily recovered and reused. This contrasts with homogeneous systems, where composition and properties are uniform throughout.
Key facts
| Field | General Chemistry |
|---|---|
| Opposite term | Homogeneous |
| Key feature | Contains two or more distinct phases |
| Common example | Heterogeneous catalysis (solid catalyst, fluid reactants) |
A mixture of sand and water is heterogeneous: the sand grains remain visibly distinct from the liquid, and the two components can be separated by simple filtration.
Frequently asked questions
What is the difference between a heterogeneous and a homogeneous mixture?
A homogeneous mixture has uniform composition and properties throughout (a single visible phase, like saltwater), while a heterogeneous mixture has non-uniform composition with distinguishable phases or regions, like oil and water.
Why is heterogeneous catalysis useful?
Because the catalyst is in a different phase from the reactants (usually a solid with gas or liquid reactants), it can be filtered out and reused, which is efficient for large-scale industrial processes like the Haber process.