Suspension vs Colloid
Mixture is an association of several substances. Suspensions, solutions, and colloids are examples of two such mixtures. Since the components in a mixture are not chemically bound together, they can be physically separated by filtration, precipitation, evaporation, etc. There are mainly two types of mixtures, homogeneous mixtures and heterogeneous mixtures. In a homogeneous mixture, the composition is uniform, but in heterogeneous mixtures, it is not uniform.
Suspension is a heterogeneous mixture of substances (E.g.: muddy water, flour dissolved in water). There are two components in a suspension, the dispersed material and the dispersion medium. There are larger solid particles (dispersed material) distributed in a dispersion medium. The medium can be a liquid, gas or a solid. However, the dispersed material is usually a solid. However, if the suspension is allowed to stand still for some time, the particles can be settled down to the bottom. By mixing it, the suspension can be formed again. The particles in a suspension are visible to the naked eye, and through filtration they can be separated. Because of the larger particles, the suspensions tend to be opaque and not transparent, because they do not transmit light.
Colloidal solution is seen as a homogeneous mixture, but it also can be heterogeneous (e.g.: milk, fog). The particles in colloidal solutions are of intermediate size (larger than molecules) compared to particles in solutions and suspensions, but like the particles in solutions, they are invisible to the naked eye and cannot be filtered using a filter paper. The particles in a colloid are termed as dispersed material, and the dispersing medium is analogous to the solvent in a solution. According to the dispersed material and the medium, there are different types of colloids. For instance, if a gas is dispersed in a liquid medium, the resulted colloid is ‘foam’ (e.g.: whipped cream). If two liquids are combined, a colloid, known as emulsion can be resulted (e.g.: milk). The particles are distributed within the colloidal medium, and do not settle down if it is left still. Colloidal solutions are translucent or opaque. Sometimes, particles in a colloid can be separated out by centrifugation or coagulation. For example, the proteins in milk are coagulated when supplied heat or added an acid.
Suspension Vs Colloid
- Suspension is a heterogeneous mixture, but colloid can be homogeneous or heterogeneous.
- The major difference between the two is the diameter of the dispersed particles; the particles in a suspension are larger than the particles in a colloid.
- The particles in a suspension can settle down under the influence of gravity, if it is undisturbed. But the particles in a colloid do not settle down under normal conditions. However, with additional forces sediments can be obtained, such as in centrifugation.
- The particles in a suspension cannot pass through a filter paper, but colloidal particles can.
- Colloids can scatter light, and suspensions do not transmit light. Therefore, colloids can be opaque or translucent, but suspensions are opaque.