Difference Between Isotonic Solution and Equilibrium

Thermodynamics is a field of chemistry that deals with the work done and heat, particularly the relationship between the two. The relation is established during ongoing chemical reactions or when any change is seen in the physical state of the reactants and products. It is not only confined to the practical calculations of the reactions but also comprises the mathematical relations and calculation related to it. 

Isotonic Solution vs Equilibrium

The main difference between Isotonic Solution and Equilibrium is that Isotonic Solution is a type of Solution in which all the constituents that are solute and solvent both are in equal proportion whereas comparatively, on the other hand, the term Equilibrium is stated as the phenomenon when the forward reaction and the backward reaction both are stable.

Isotonic Solution and Equilibrium

Isotonic Solution is one of the three types of Solution known apart for this – hypertonic Solution and the hypotonic Solution is known. The Solution can acquire an isotonic condition when both the constituent that is solute and solvent persists in the same concentration. A good example of such a condition is the blood cells of the human body. They allow the nutrients, water, and other materials to pass through its membrane to carry oxygen mainly.

Equilibrium is a condition in the chemical solution when both the reactants and products are stable or at an equal rate. In other words, the forward and reverse reaction occurs such that the resultant product is obtained, which again breakdown in the reactants. For a respective reaction, the reaction rate of the forward one and for the reverse one might be the same but never tends to be zero in equilibrium.

Comparison Table Between Isotonic Solution and Equilibrium

Parameters of ComparisonIsotonic SolutionEquilibrium
Discovered BySydney RingerGibbs and Le Chatelier
DefinitionThe concentration of constituent (solute and solvent) passing by the semi-permeable membrane is the sameWhen forward and reverse reactions are balanced or stable
Preparation Can be manually preparedCannot be prepared manually as it attains it by itself
Physical ParametersNo such effectAffected by the rate of reaction, temperature, pressure, etc
MovementNo movement is shown because of the same concentration gradientNo movement because of zero net force

What is Isotonic Solution?

Osmosis is a phenomenon of water movement taking place in and out by a semi-permeable membrane. This is further sub-divided into three types of Solution that is – Hypotonic Solution, Hypertonic Solution, and Isotonic Solutions. Isotonic Solution is where the concentration gradient of the Solution is the same (of the solute and solvent) passing by the semi-permeable membrane.

The word itself means equal, and thus the movement of both solute and solvent is equal. The phenomenon of the isotonic Solution was discovered by Sydney Ringer in the year 1882. The phenomenon of isotonic Solution can be established in the laboratory by preparing it manually.

The isotonic solution is said to be not affected by any external factors such as – the rate of reaction, pressure, temperature, etc. Also, the movement of particles is so slow in the Solution that it isn’t even noticeable.

What is Equilibrium?

Equilibrium is a phenomenon of the chemical reaction in which it attains considerable stability. In other words, when the two reactions that are forward in which the reactants change into product and the backward reaction in which the products again break down to form reactants attains stability at a considerable point where the reactants can be further broken, and the product doesn’t break back to form reactants.

The word equilibrium itself means equal and stability. Besides this, the phenomenon of equilibrium was discovered by Gibbs and Le Chatelier, and they both worked upon it in a different timeline that is Gibbs worked from 1873-1878 while Le Chatelier worked in 1875. Further, many other scientists also worked on this discovery.

Perhaps the phenomenon is affected by external factors like – reaction rate, temperature, pressure, etc. And the movement is unnoticed because of the forces working on it that are not equal to zero.

Main Differences Between Isotonic Solution and Equilibrium

  1. The phenomenon of Isotonic Solution was discovered by the scientist Sydney Ringer whereas comparatively, on the other hand, the phenomenon of Equilibrium was discovered by the two scientists Gibbs and Le Chatelier.
  2. The discovery of the isotonic solution phenomenon was made in the year 1882, whereas comparatively, on the other hand, the discovery of the equilibrium phenomenon was made first in the year 1873, and then later, different scientists worked on it on a different timeline.
  3. The phenomenon of the isotonic Solution can be stated as to when the concentration gradients of a solution (both solute and solvent) passing by the semi-permeable membrane are the same whereas comparatively, on the other hand, the phenomenon of the equilibrium can be stated as the forward and backward reaction of the Solution are stable.
  4. The Solution of defining isotonic Solution can be manually prepared, whereas comparatively, on the other hand, the equilibrium reactions can not be manually prepared as they attain it themselves at a particular point. 
  5. The isotonic Solution eventually doesn’t get affected by the external physical factors, whereas comparatively, on the other hand, the equilibrium phenomenon tends to be affected by the external phenomenon such as – temperature, pressure, concentration, reaction rate, etc.
  6. In an isotonic solution, the movement of constituents by the semi-permeable membrane is very slow, and it thus occurs by the process of osmosis, whereas comparatively, on the other hand, in the equilibrium, the movement isn’t noticeable because of the equal net force that is zero.  


To summarize the above discussion, the terms mentioned have the priorly same meaning as a whole. Isotonic and Equilibrium is other terms used in place of balance and stability, but in Chemistry, the meaning gets changed. Despite having the same meaning, they are two different phenomena or processes attaining balance. With the isotonic Solution, the gradient persists two things solvent and solute having the same concentration, and they move with equal rate by a semi-permeable membrane.

Such movements are unnoticeable through naked eyes, whereas comparatively, on the other hand, in the case of equilibrium, the gradient or the Solution has two reactions ongoing that are the forward reaction with reactants breaking into products and the reverse that is products breaking back into reactants. The rate of this movement of chemicals is unnoticeable.


  1. https://link.springer.com/article/10.1007/BF02989804
  2. https://pubs.acs.org/doi/pdf/10.1021/je60058a011
  3. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2818.1985.tb02641.x
  4. https://wires.onlinelibrary.wiley.com/doi/abs/10.1002/wcs.108
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