Lyophilic
Definition and meaning of Lyophilic in chemistry.
"Lyophilic" describes a colloid or substance that has a strong affinity for the dispersing medium (solvent) and readily dissolves or disperses in it. Lyophilic colloids form stable solutions and naturally resist coagulation or precipitation.
In more detail
The term comes from Greek roots meaning "solvent-loving." In aqueous systems, lyophilic substances are also called hydrophilic. The remarkable stability of lyophilic colloids arises from favorable molecular interactions (hydrogen bonding, electrostatic attraction, or other favorable solvation effects) between the dispersed phase and solvent molecules. This molecular compatibility explains why lyophilic colloids resist coagulation when electrolytes are added, unlike lyophobic colloids which readily precipitate under those same conditions.
Key facts
| Etymology | From Greek 'lyo' (to dissolve) and 'philic' (affinity for) |
|---|---|
| In aqueous systems | Also called hydrophilic |
| Opposite | Lyophobic (solvent-repelling) |
| Field | Physical Chemistry |
Gelatin dissolved in hot water forms a stable lyophilic colloid because gelatin molecules are long-chain proteins with polar amino acid residues that extensively hydrogen-bond with water, creating a persistent solvation shell even as the solution cools.
Frequently asked questions
What distinguishes a lyophilic from a lyophobic colloid?
Lyophilic colloids have strong affinity for the solvent and form stable solutions that resist coagulation, while lyophobic colloids repel the solvent and readily aggregate when electrolytes are added.
Why do proteins in water typically form lyophilic colloids?
Proteins contain polar amino acid residues on their surfaces that form extensive hydrogen bonds with water molecules, creating favorable solvation that keeps the protein well-dispersed.