Difference Between Tonicity and Osmolarity

Thekey differencebetween tonicity and osmolarity is that thetonicity measures only the concentration of non-penetrating solutes through a semipermeable membrane whilethe osmolarity measures the total concentration of penetrating and non-penetrating solutes.

Osmolarity is the measure ofosmotic pressureof a solution. In simpler terms, it is roughly the measure of the amount of solute in the solution. On the contrary, tonicity refers to the relative专注细胞内部的溶质颗粒相对于细胞外部的浓度。因此，音质和渗透压似乎都是相似的概念。但是，我们将在本文中讨论一些差异。

CONTENTS

1.Overview and Key Difference
2.什么是补品
3.What is Osmolarity
4.Side by Side Comparison – Tonicity vs Osmolarity in Tabular Form
5.概括

什么是补品?

Tonicity is a measure of the osmotic pressure gradient by means of water potential of two solutions separated by a semipermeable membrane. It means; the term tonicity describes the relative concentration of solutes I solution which determines the direction and extent of diffusion. This measurement is important in determining the response of cells that are immersed in an external solution.

与渗透压力不同，这种补体仅受无法穿过膜的溶质的影响。可以自由地穿过膜的溶质对这种质量没有影响。这是因为，这些溶质的浓度在膜的两侧始终保持不变。通常，我们对另一种解决方案表示平衡。因此，基于补体的三种类型的解决方案。hypertonic solutions, hypotonic solutions, andisotonic solutions。高渗溶液比另一种溶液具有高溶质浓度，而低渗溶液的溶质浓度较低。如果该溶液的有效渗透浓度与另一种溶液的有效渗透浓度相同，则将成为等渗。

What is Osmolarity?

Osmolarity or osmotic concentration is a measure of solute concentration given by the unit osmoles of solutes per litre of solution. We can denote the unit as Osm/L. Likewise, we can use this value to measure the osmotic pressure of a solution. Thus, the tonicity of the solution as well. The equation that we can use to measure this parameter is as follows:

渗透压= ∑ψ_in_iC_i

Here, ψ is the osmotic coefficient, n is the number of particles into which a molecule dissociates, and C is the molar concentration of the solute. Likewise, there are three types of solutions according to the osmolarity; isosmotic, hyperosmotic and hypoosmotic.

What is the Difference Between Tonicity and Osmolarity?

The terms tonicity and osmolarity are related but distinct concepts. The reason why they are related to each other is that both these terms compare the solute concentrations of two solutions separated from a semipermeable membrane. These terms differ from each other according to the type of solute they take into account when measuring. Therefore, the key difference between tonicity and osmolarity is that tonicity measures only the concentration of non-penetrating solutes through a semipermeable membrane whereas osmolarity measures the total concentration of penetrating and non-penetrating solutes.

The below infographic gives further facts on the difference between tonicity and osmolarity.

概括– Tonicity vs Osmolarity

The terms osmolarity and tonicity are inter-related as both these terms compare the solute concentrations in a solution. But, at the same time, the terms are distinct chemical concepts according to the types of solutes that they take into account in their measurements. Hence, the key difference between tonicity and osmolarity is that the tonicity measures only the concentration of non-penetrating solutes through a semipermeable membrane whereas the osmolarity measures the total concentration of penetrating and non-penetrating solutes.

Reference:

1. “Tonicity.” Wikipedia, Wikimedia Foundation, 8 Feb. 2018.Available here
2. “Osmotic Concentration.” Wikipedia, Wikimedia Foundation, 15 Oct. 2018.Available here

Image Courtesy:

1.”Osmotic pressure on blood cells diagram”By LadyofHats – Own work (Public Domain) viaCommons Wikimedia