Search results
Results from the WOW.Com Content Network
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid , [ 1 ] while others extend the definition to include substances like aerosols and gels .
Another example of non-Newtonian fluid flow is chilled caramel ice cream topping (so long as it incorporates hydrocolloids such as carrageenan and gellan gum). The sudden application of force —by stabbing the surface with a finger, for example, or rapidly inverting the container holding it—causes the fluid to behave like a solid rather than ...
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. Examples include amongst others blood, pigmented ink, cell fluids, paint, antacids and mud.
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.
Colloids are formed by phase separation, though not all phase separations forms colloids - for example oil and water can form separated layers under gravity rather than remaining as microscopic droplets in suspension. A common form of spontaneous phase separation is termed spinodal decomposition; it is described by the Cahn–Hilliard equation.
In their paper, they give many more examples of colloid systems that flocculate into an emulsoid state, either by varying the temperature, by adding salts, co-solvents or by mixing together two oppositely charged polymer colloids, and illustrate their observations with the first microscope pictures of coacervate droplets.
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 ...
In addition, a heterogeneous mixture may have a uniform (e.g. a colloid) or non-uniform (e.g. a pencil) composition. Several solid substances, such as salt and sugar , dissolve in water to form homogeneous mixtures or " solutions ", in which there are both a solute (dissolved substance) and a solvent (dissolving medium) present.