Isotonic solutions are a special group of solutions that are characterized by osmotic pressure. It has the meaning that characterizes fluids in the body, such as: blood plasma, tears, lymph, and so on. All these fluids have a constant pressure in the region of 7.4 atm. Moreover, if an injection is introduced into the body, then the osmotic pressure of the fluids will be disturbed, since a similar balance will be disturbed.
In order to prepare such a solution, it is necessary to make some calculations. The most famous way to conduct them is nothing other than the isotonic coefficient of Vant Hoff. Using it, you can calculate the isotonic concentration of a solution of a dilute substance that is not an electrolyte. The osmotic pressure, the amount of solution, as well as its temperature are in a certain relationship, which is expressed by the Klaipedon equation. It is used in relation to dilute solutions, since according to the Van Goff law, substances dissolved in liquids will behave in the same way as gases, and therefore all the so-called gas laws apply to them .
The isotonic coefficient is nothing more than a parameter that will characterize the behavior of a substance in any solution. If we talk about the numerical equivalent, then the isotonic coefficient is equal to the ratio of the numerical value of the colligative property that the solution has to the same property of the non-electrolyte, with the same concentration, while all other parameters remain unchanged.
The physical meaning of the isotonic coefficient becomes clear on the basis of the definition of each colligative parameter. All of them are dependent on the concentration of the substance in the particle solution. Non-electrolytes will not enter into dissociation reactions, so each individual molecule of such a substance will be a single particle. In the process of solvation, electrolytes will either completely or partially decay into ions, while forming several particles. It turns out that the colligative properties of the solution will depend on the amount of particles of different types contained in it, that is, ions. Thus, the isotonic coefficient will be a mixture of different solutions of each type of particle. If we consider a solution of bleach, then we can see that it consists of three types of particles: calcium cations , hypochlorite, and also chloride - anions. The isotonic coefficient will indicate that there are more particles in the electrolyte solution than in the non-electrolyte solution. The coefficient will directly depend on whether the substance can decay into ions - this is nothing more than a property of dissociation.
Since strong electrolytes are completely subjected to dissociation processes, it is quite reasonable to expect that the isotonic coefficient in this case will be equal to the number of ions contained in the molecule. However, in reality, the value of the coefficient will always be less than the value calculated by the formula. This position was substantiated back in 1923 by Debye and Hückel. They formulated the theory of strong electrolytes: ions will not move with obstacles, since a solvation shell will form. Moreover, they will also interact with each other, which will lead, in the end, to the formation of their group, which will move in one direction along the solution. These are the so-called ionic associations, as well as ionic pairs. All processes in the solution will occur in such a way as if it contains few particles.
The interaction of ions will begin to weaken as the temperature rises, as well as their concentration decreases. Everything is explained by the fact that in this case the probability of meeting different particles in the solution will also decrease.