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An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles, in particular two-stroke machines where the burnt engine oil provides these particles. [1] The same effect can also be observed with tobacco smoke whose fine particles also preferentially scatter blue light.
This distinguishes a suspension from a colloid, in which the colloid particles are smaller and do not settle. [2] Colloids and suspensions are different from solution , in which the dissolved substance (solute) does not exist as a solid, and solvent and solute are homogeneously mixed.
A solute in a solution are individual molecules or ions, whereas colloidal particles are bigger. For example, in a solution of salt in water, the sodium chloride (NaCl) crystal dissolves, and the Na + and Cl − ions are surrounded by water molecules. However, in a colloid such as milk, the colloidal particles are globules of fat, rather than ...
A sol is a colloidal suspension made out of tiny solid particles [1] in a continuous liquid medium. Sols are stable, so that they do not settle down when left undisturbed, and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. The size of the particles can vary from 1 nm - 100 nm.
Ketchup, for example, becomes runnier when shaken and is thus a non-Newtonian fluid. Many salt solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as custard, [1] toothpaste, starch suspensions, corn starch, paint, blood, melted butter and shampoo.
Unlike solutions and colloids, if left undisturbed for a prolonged period of time, the suspended particles will settle out of the mixture. Although suspensions are relatively simple to distinguish from solutions and colloids, it may be difficult to distinguish solutions from colloids since the particles dispersed in the medium may be too small ...
As an example, consider a colloidal suspension of polyethylene particles in water, and three different values for the diameter of the particles: 0.1 μm, 1 μm and 10 μm. The volume of a colloidal particles can be calculated using the volume of a sphere V = 4 3 π R 3 {\displaystyle V={\frac {4}{3}}\pi R^{3}} .
When both large colloidal particles and small depletants are in a suspension, there is a region which surrounds every large colloidal particle that is unavailable for the centers of the depletants to occupy. This steric restriction is due to the colloid-depletant hard-sphere potential. [7] [8] The volume of the excluded region is