Problem 7 - A Complete Resource Book in Chemistry for JEE Main

Question

During osmosis, flow of water through a semipermeable membrane is (a) from both sides of semi-permeable membrane with unequal flow rates (b) from solution having lower concentration only (c) from solution having higher concentration only (d) from both sides of semi-permeable membrane with equal flow rates

Step-by-Step Solution

Answer

The correct answer is (b): from solution having lower concentration only.

Step 1: Understanding Osmosis

Osmosis is the movement of water molecules through a semipermeable membrane. The direction of movement is from an area of lower solute concentration to an area of higher solute concentration.

Step 2: Identifying Key Terms

A semipermeable membrane allows only certain molecules to pass through. In the context of this question, it allows water to move while preventing solutes from passing.

Step 3: Analyzing Each Option

(a) suggests water flows with unequal rates from both sides, which is incorrect for osmosis. (b) suggests water flows from lower concentration only, which aligns with osmosis. (c) suggests movement from higher concentration, which contradicts osmosis principles. (d) suggests equal rates from both sides, not typical for osmosis.

Step 4: Selecting the Correct Answer

Based on our understanding of osmosis, the correct option is (b), which states that water flows from a solution having a lower concentration of solute to a solution with a higher concentration of solute.

Key Concepts

Semipermeable Membrane

In the process of osmosis, a semipermeable membrane plays a crucial role. This type of membrane acts as a selective barrier. It allows only specific molecules to pass through, primarily water molecules, while blocking others, such as solute particles. Think of a semipermeable membrane as a very fine filter. It helps maintain a balance by permitting the movement of water based on concentration gradients.

Imagine a semipermeable membrane as a smart wall standing between two solutions. It selectively decides who gets to cross based solely on size and other properties. Important in biological systems, it aids in the transportation and balance of nutrients and waste. Note how these membranes are vital in processes like kidney function, where they filter out waste materials from the blood.

Keep in mind that osmosis through a semipermeable membrane is a passive process. It does not require energy input. The driving force here is simply the difference in concentration between the two sides of the membrane.

Water Molecules

Water molecules are small, allowing them to move freely across a semipermeable membrane during osmosis. Water's ability to move easily is what makes osmosis efficient and effective. This movement is crucial in many biological processes, contributing to cell hydration and nutrient transport.

Water tends to move towards areas with higher solute concentration because it seeks to balance the concentration differences. This is nature's way of achieving equilibrium. In living organisms, this movement of water helps cells maintain their shape and function.

When discussing osmosis, appreciating water's properties highlights its importance. Its small size and polar nature make it a universal solvent, facilitating the efficient transport of nutrients and waste products. This explains why osmosis is such a vital process for life.

Solute Concentration

Solute concentration refers to the amount of solute particles present in a given solution. During osmosis, this concentration gradient across a membrane dictates the direction water moves. High solute concentration means fewer free water molecules, creating an area that naturally attracts water from regions of lower solute concentration.

Imagine solute concentration as a lure for water. The higher the concentration, the stronger the pull exerted on water molecules. This concentration difference is what drives osmosis without the need for energy.

Solute concentration helps cells regulate their internal environments. In plants, for instance, a high external solute concentration can draw water out, causing wilting. However, in balanced conditions, cells are able to maintain turgor pressure, essential for structural integrity and function. Understanding solute concentration is key to grasping how organisms survive and adapt to varying environmental conditions.