When we dissolve sugar or table salt in water, after some time sugar or salt completely dissolve in water and we cannot even see the particles of sugar or salt. Now if you repeat same thing with sand, did you get same results?
Sugar, salt, water, sand are different substances but when they mix with each other, did they form again another substance? All the substances can be classified as element, compound and mixture. Out of these three, element and compound are pure substance as they form by same or type of atoms. Water, salt and sugar are good examples of compounds.
Mixtures are formed by the combination of two or more compounds. Here sugar or salt in water are examples of mixtures. Now see the mixture of sugar in water and sand in water. Do they have some difference? Yes… It is.
The solution of sugar in water is a clear solution whereas sand in water is not a clear solution. After some time, sand settles at the bottom and we can see the particles of sand clearly. Now compare these two solutions with milk. Milk is not a clear solution but particles do not settle at the bottom with time. So we can say that particles remain dispersed in solution but the size is big enough that does not allow the clear appearance of solution.
On the basis particles size, mixtures can be classified as true solution, colloids and suspension. The particles in true solutions are very tiny so that we cannot see them with naked eyes. A true solution is composed of two components; solute (less amount) and solvent (more quantity). They are commonly called as solutions only such as sugar in water or salt in water.
Suspensions have particles with quite bulky in size therefore they readily settle down at the bottom. That is why suspensions are heterogeneous mixtures such as sand in water. Colloids have intermediate particle size so that particles remain dispersed in medium but cannot see by naked eyes. Here the particles are called as dispersed phase and the medium is called as dispersion medium. Fog, milk, smoke and gel are some common examples of colloidal solutions.
Suspensions are Cloudy, heterogeneous mixtures of at least two substances which are clearly visible in the solution. The particle size in such solutions is larger than 10,000 Angstroms so that they can even seen by naked eyes.
Letâs take a scoop of sandy water and place in bottle. Shake it and observe the change. Does sand dissolve in water or not? Sand will float and settle to the bottom after some time. Because of coarse particle size, when we pass the beam of light through the solution, it scatters and the path of light is visible. A suspension can be considered as an unstable solution in which the particles can settle down if left undisturbed.
Such mixtures are called as suspension. Sand in water is one of the most common examples of suspensions. It is a type of heterogeneous mixture in which solid particles do not dissolve in a medium even after shaking. You can consider these suspended particles as stubborn substances which have unwilling to dissolve in a solution. Suspensions are heterogeneous mixtures which have non-uniformity throughout the mixture. That is the reason; the components of heterogeneous mixtures can be separated by physical methods.
As we discussed, suspension is a heterogeneous mixture in which particles are distributed in certain medium and can be easily separate out by physical methods. You can observe many suspension solutions in everyday life. Muddy water, paint, and medicines such as Pepto-Bismol, milk of magnesia, finger paints, red blood cells in blood plasma are some examples of suspensions.
In chemistry, suspension can be defined as the heterogeneous mixture in which both components can be separated by physical means. In most of the suspensions, solid particles are mixed with some liquid medium. But we have some examples in which both the phases are liquid state only. Overall in suspension, the components can separate over time and particles do not dissolve in the fluid. Mercury with oil, oil with water, powdered chalk in water and dust and soot in air are some examples of suspensions.
Suspensions contain deformable particles as disperse system with liquid as dispersion medium. The particle size of suspensions is ranging from colloidal to coarse. They exhibit quite similar rheological behavior with emulsions, foams and colloidal suspensions. Many foods are suspensions in which continuous phase remains in an aqueous medium so they are also considered as colloidal suspensions. Most of the commercial food suspensions exhibit viscous laminar flow in pumping processes. This is because of their high apparent shear viscosity. Dressings as mustard seeds, Mexican sauces with seeds, cream soups, pasta products, meat in sauces, meat balls, and yogurts with fruits are some examples of suspensions.
Today we have a wide range of cosmetics available in market. Cosmetics are usually marketed as solutions, lotion, cream, suspensions, ointments or pastes, powder, gel, sticks and tablets. Suspensions are mainly used for overcoming the incompatible ingredients.
Just like creams, suspensions are clear solutions with visible particles like gelatin beads, inorganic minerals etc. These particles remain spread throughout the solution. Some common examples of suspensions are sunscreens, hand washes and shampoos.