Colloids (also known as colloidal solutions or colloidal systems) are mixtures of insoluble particles.
They show dispersion of one substance that are microscopic in nature, and show suspension in another substance.
The size of these suspended particles in a colloid can vary from 1 to 1000 nanometres (10-9 metres).
A colloid is a mixture of particles between 1 and 1000 nanometers in diameter, yet it is still capable of evenly spreading throughout the solution.
They are also refer to as colloidal dispersions because the substances remain in dispersion and do not settle down on the bottom of the container.
However, the condition remains that for a mixture to be termed as colloid
The suspended particles present in the mixture must not settle down,
The way that the particles of suspensions settle at the bottom of the container if left undisturbed.
Solutions in colloidal state display tyndall effect, wherein the beam of light incident on colloids exhibit scattering due to the interactions between the colloidal particles and light.
IUPAC Definition of Colloids
The IUPAC definition of the colloidal state is as follows:
“The colloidal state is the state of subdivision in which molecules or polymolecular particles having at least one dimension in the range of 1 nanometre and 1 micrometre, and show dispersion in some medium “. Colloids usually feature substances that are evenly show dispersion in another.
Such mixtures where the substance showing dispersion is called as the dispersion phase and the substance through which dispersion is taking place is the continuous phase
In simple terms, colloids are a mixture where one of the substances are split into minute particles.
Therefore, we define colloids as a mixture where one of the substances is split into very minute particles and which can disperse throughout a second substance. The minute particles are colloidal particles.
Alternatively, we can also say that colloids are basically solutions in which solute particle size ranges from 1nm – 1000 nm. Colloids are heterogeneous in nature
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