The blood of cold-blooded animals and fish is isotonic with...

The blood of cold-blooded animals and fish is isotonic with seawater. If seawater freezes at $-2.3{ }^{\circ} \mathrm{C},$ calculate the osmotic pressure of the blood of these animals at $20.0^{\circ} \mathrm{C}$. (Assume the density is that of pure water.)

Key Concepts

Colligative Properties

Colligative properties are characteristics of solutions that depend solely on the ratio of solute particles to solvent molecules and not on the chemical identity of the solute. They include phenomena such as freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure. These properties are fundamental in understanding how the addition of a solute influences the physical behavior of a solvent.

Freezing Point Depression

Freezing point depression is a colligative property where the freezing point of a solvent is lowered by the presence of a solute. This effect occurs because the solute particles interfere with the formation of a regular crystal lattice in the solvent, requiring a lower temperature to achieve the transition from liquid to solid. It is mathematically related to the molality of the solution and the cryoscopic constant of the solvent.

Osmotic Pressure

Osmotic pressure is the pressure required to prevent the net flow of solvent molecules across a semipermeable membrane separating two solutions of different concentrations. It is directly proportional to the molarity of the solute and the absolute temperature, and is calculated using an equation analogous to the ideal gas law. This concept is critical in understanding fluid exchange in biological systems and in various industrial applications.

van’t Hoff Factor

The van’t Hoff factor (i) describes the number of particles into which a solute dissociates in solution. It is used in calculations of colligative properties, such as freezing point depression and osmotic pressure, to adjust for the effect of dissociation or association of solute particles. In cases where the solute does not dissociate, the factor is typically unity, but for electrolytes it is greater than one, reflecting the increased number of particles present.

Isotonic Solutions

Isotonic solutions refer to solutions that have the same osmotic pressure, or more generally the same solute concentration, as a reference solution, often a biological fluid such as blood. In biological contexts, maintaining isotonic conditions is essential to avoid net movement of water across cell membranes, which can lead to cell swelling or shrinkage. This concept is important for understanding fluid balance in organisms and the physiological compatibility of intravenous solutions.

Transcript

Please give Ace some feedback