Question

In the case of osmosis, solvent molecules move from : (a) Higher vapour pressure to lower vapour pressure (b) Higher concentration to lower concentration (c) Lower vapour pressure to higher vapour pressure (d) Higher osmotic pressure to lower osmotic pressure

Short answer

In the case of osmosis, solvent molecules move from a region of higher osmotic pressure to a region of lower osmotic pressure.

Step-by-step solution

Understanding Osmosis

Osmosis is the process by which solvent molecules pass through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration. This movement also implies that there is an associated movement from higher solvent concentration to lower solvent concentration, since solute concentration and solvent concentration have an inverse relationship.

Analyzing Options

To find the correct option, consider how osmosis is governed by solute concentration which also aligns with osmotic pressure. The movement of solvent molecules occurs from an area of higher solvent concentration (lower solute concentration, lower osmotic pressure) to an area of lower solvent concentration (higher solute concentration, higher osmotic pressure).

Determining the Correct Statement

Since osmotic pressure is directly related to solute concentration, the movement of solvent molecules in the case of osmosis is from a region of lower solute concentration and higher solvent concentration (which corresponds to lower osmotic pressure) to a region of higher solute concentration and lower solvent concentration (which corresponds to higher osmotic pressure). Thus, the correct statement regarding osmosis is 'Higher osmotic pressure to lower osmotic pressure.'

Key concepts

Solvent Concentration

Understanding solvent concentration is crucial when studying osmosis. In a solution, a solvent is the substance that dissolves the solute to form the solution. Commonly, water serves as the solvent. The solvent concentration refers to the amount of solvent present in a given volume of solution. During osmosis, solvent molecules naturally migrate from an area where they are more plentiful, which means a high solvent concentration, to an area where they are less plentiful, or a low solvent concentration. The process will continue until equilibrium is reached and the solvent concentrations are equal on both sides of a membrane.

Osmosis can be observed in biological systems, where water may enter or leave a cell due to the concentration differences across the cell membrane, which acts as a semi-permeable barrier. The comprehension of this concept is fundamental for the explanation of various physiological processes, such as the maintenance of cell shape and the transport of nutrients and waste products.

Solute Concentration

In contrast to solvent concentration, solute concentration refers to the amount of solute that is dissolved in a given volume of solution. A solute can be a solid, liquid, or gas that is dissolved by a solvent. The solute concentration has an inverse relationship with solvent concentration because if you increase the amount of solute in a solution, you have less free solvent available. Therefore, in osmosis, a higher solute concentration implies a lower free solvent concentration in that area.

When solute concentration differs on either side of a semi-permeable membrane, solvent molecules move to try to equalize the concentration. This movement from a region of lower solute concentration (which means higher solvent concentration) to a region of higher solite concentration (lower solvent concentration) is a key mechanism driving osmosis. Understanding solute concentration allows students to predict the direction in which water or other solvents will move across a membrane in many scientific and medical scenarios.

Osmotic Pressure

Osmotic pressure is the hydrostatic pressure required to stop the flow of solvent molecules through a semi-permeable membrane. It's a measure of the tendency of a solvent to move into a more concentrated solution. The pressure arises due to the solute concentration on either side of a membrane, and it drives solvent molecules from the region of lower osmotic pressure (less solute, more solvent) to the region of higher osmotic pressure (more solute, less solvent).

Osmotic pressure can have significant biological implications, for example, it can affect the fluid balance in the human body. If blood cells are placed in a solution with high osmotic pressure, water will move out of the cells, possibly causing them to shrink. Conversely, if they are in an environment with lower osmotic pressure, water will enter the cells, which could lead to swelling or even bursting. Hence, osmotic pressure is a fundamental concept in understanding fluid distributions in living organisms and the overall functioning of cells.

Semi-Permeable Membrane

A semi-permeable membrane, also known as a selectively permeable or partially permeable membrane, is a barrier that allows certain substances to pass through while blocking others. In the context of osmosis, this membrane will enable the free movement of solvent molecules - most commonly water - but not the solute particles. These membranes are crucial in biological systems, as they are a key component of cell membranes. They allow cells to control the movement of substances in and out, which is essential for maintaining homeostasis.

The properties of a semi-permeable membrane determine the effectiveness and direction of osmosis. The ability of a cell membrane to regulate internal conditions is founded on the selective permeability to various substances, which can result in complexities such as the generation of electrical potentials across the membrane. Understanding the role of semi-permeable membranes helps to explain numerous physiological processes, including nutrient uptake, waste removal, and even the transmission of nerve signals in the body.