Both in everyday life and in the scientific field, there are very frequent mixtures that involve a solid component and another liquid. In a mixture of this type, the solid is usually in less quantity than the liquid, although this is not always the case. This distribution is merely proportional and, when it comes to a solution, the majority substance acquires the name of solvent and the minority the name of solute. For instance: syrup, petroleum, alcohol ink.
On some occasions the process to mix Several substances are simple, while others require the use of specially constituted devices for this purpose. In the food, cosmetic, pharmaceutical and chemical industries, the mixer is often used, which recirculates the solids through a tank, and they are placed manually or automatically in a hopper. This is common for mixes that would be very difficult to prepare manually.
Mixtures of solids in liquids can be presented in different ways, according to the characteristics of these components:
- Solutions. The formation occurs by the disaggregation of the solid down to the molecular or ionic level. It is common for the solids that are part of the solutions to dissolve well in the solvent, forming a homogeneous mixture (a fundamental characteristic of solutions).
- Suspensions. They are mixtures that do not reach the state of dissolution since the solid particles can be seen with the naked eye or with a microscope. This gives the compound a cloudy appearance as you can see the particles of the solid suspended (floating) in the liquid.
- Colloids. They are the combinations of substances whose differences in their particles are not visible to the naked eye (although they can only be seen under an electron microscope). Colloids have properties intermediate between solutions and suspensions.
The mixtures between solids and liquidsLike the other classes of mixtures, they have different ways of separating their components: science has been very involved in achieving this objective, fundamental for many uses and applications. Some processes to carry out this division are:
- Centrifugation. It is the same technique that is used to remove water in dishwashers or clothes washers.
- Crystallization. One of the ways to apply this method is by removing all of the solvent by means of rapid evaporation (in this way, the dissolved solids begin to crystallize). This procedure is used to obtain common salt.
- Chromatography. This separation process is based on the selectivity of each component of a mixture for a stationary phase (a substance that remains fixed and retains the component with the highest affinity for it) and a mobile phase (a substance that flows through the stationary phase and drags the component with the highest affinity for this mobile phase).
- Sedimentation. It is the procedure of leaving the mixture at rest, so that the solid component is deposited or precipitated, thus it can be separated from the liquid.
Examples of Mixtures of Solids and Liquids
| Syrups | Blood (colloidal mixture) |
| Cement (mix of water with sand) | Broth |
| Petroleum | Yogurt (usually in a colloid-like state) |
| Powder juices | Ink with alcohol |
| Mud (typical mixture of cloudy character) | Mix of washing powder and water |
| Cheese | Saline solution (water and salt) |
| Filter coffee dissolved in water | Dairy formulas (protein and water) |