Equilibrium and dynamic osmotic behaviour of aqueous solutions with varied concentration at constant and variable volume.
Osmosis is essential for the living organisms. In biological systems the process usually occurs in confined volumes and may express specific features. The osmotic pressure in aqueous solutions was studied here experimentally as a function of solute concentration (0.05-0.5 M) in two different regimes: of constant and variable solution volume. Sucrose, a biologically active substance, was chosen as a reference solute for the complex tests. A custom made osmotic cell was used. A novel operative experimental approach, employing limited variation of the solution volume, was developed and applied for the purpose. The established equilibrium values of the osmotic pressure are in agreement with the theoretical expectations and do not exhibit any evident differences for both regimes. In contrast, the obtained kinetic dependences reveal striking divergence in the rates of the process at constant and varied solution volume for the respective solute concentrations. The rise of pressure is much faster at constant solution volume, while the solvent influx is many times greater in the regime of variable volume. The results obtained suggest a feasible mechanism for the way in which the living cells rapidly achieve osmotic equilibrium upon changes in the environment.
Department of Chemistry and Biochemistry, Physiology and Pathophysiology, Faculty of Medicine, Sofia University, 1 Kozyak Street, 1407 Sofia, Bulgaria ; Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria.
Ivan L
IL
Minkov
Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria.
Emil D
ED
Manev
Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria.
Svetla V
SV
Sazdanova
Faculty of Mathematics and Informatics, Plovdiv University, 24 Tzar Assen Street, 4000 Plovdiv, Bulgaria.
Kiril H
KH
Kolikov
D009995:Osmosis; D012996:Solutions / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D012996:Solutions; D014867:Water