Osmosis and Osmotic Pressure: Osmosis, Osmotic Pressure, Examples of Osmosis and Osmotic Pressure, Practice Problems, FAQs

You might have seen plants wilting on lack of water, blossoming on getting enough water, and decaying in the presence of excess water. This shows that water is taken up by the plant cell and the quantity inside greatly affects the stature of the plant. What controls the intake of the water by the cell? The answer is a process called osmosis and the related osmotic pressure.

Most plants rely on osmotic pressure to maintain the shape of their stems and leaves. If we have ever kept potted plants, we are aware that they may become very wilted if they are not watered regularly, for an extended period of time. After watering, they can be instantly perked back up.

The salts in the cells allow water to enter through the semipermeable cell wall by osmosis, giving the cell a plump and hard exterior. The plant will wilt if there is not enough water because its cells become "deflated." They are said to be "hypertonic," which in scientific terms means "the concentration of solute is too high."

Do you know the effect of this osmosis? You might see plants growing out of asphalt/ concrete walls, in buildings. This is due to the development of a high osmotic pressure in plants. As plants grow, their cells draw in more water. The slow but constant pressure of water passing through the membranes of plant cells can really push through asphalt. At the same time, the presence of larger amounts of water inside the cell than necessary may result in breaking up of the cell walls leading to decay of the plant.

This is not true for plants only but for all living things. Human beings are hypertonic on dehydration and need to be administered immediately with saline water.

Table of contents:

• Osmosis
• Osmotic Pressure
• Examples of Osmosis and Osmotic Pressure
• Practice Problems
• Frequently Asked Questions

Osmosis:

Osmosis is the movement of solvent molecules from a region of higher concentration of solvent to a region of lower concentration of solvent through a partially or selectively permissible partition or membrane

Osmotic Pressure:

Osmotic pressure is the required force or pressure to be applied on the solution side to prevent the spontaneous flow of the solvent across the semipermeable membrane into the solution side.

Small solvent molecules but not large solute molecules can pass through a semipermeable membrane, which is a selective barrier made up of microscopic pores.

Initially, an animal leather membrane known as a semipermeable membrane was used as a partially permitting semi-permeable substance. However, it can be made of synthetic polymers or natural polymers derived from plant or animal sources.

Mathematical Representations of Osmotic Pressure:

Van't Hoff observed that osmotic pressure of a dilute solution is proportional to the molarity C of the solution at a given temperature T. Osmotic pressure being dependent on the concentration , it is a colligative property. The relation can be written as,

… … … … … (1)

Where = Osmotic pressure

= is the proportionality constant = Universal gas constant

… … … … … (2)

Where is the volume of the solution in containing of solute.

If grams of the solute of molar mass is present in the solution, then

… … … … … (3)

Substituting (3) in (2),

Or … … … … … (4)

Thus, if other quantities like , , and are known, we can calculate the molar mass of the unknown solute.

The influence of solutes on the colligative properties of solutions is explained by the Van't Hoff factor. The Van't Hoff factor is represented by the letter "i." The amount that a substance associates or dissociates in a solution is described by the Van't Hoff factor.

The relationship between van’t Hoff factor and osmotic pressure is given by the below equation

= Osmotic pressure

= is the proportionality constant = Universal gas constant

Van’t Hoff factor

concentration of the solution.

Types of solutions:

1. Isotonic solutions:A pair of solutions that have the same osmotic pressure are said to be isotonic.

2. Hypertonic solutions:A solution is referred to as being hypertonic if it has a higher osmotic pressure than another solution.

3. Hypotonic solution: A solution is referred to as a hypotonic solution if its osmotic pressure is lower than that of another solution.

Examples of osmosis and osmotic pressure:

1. Blood purification by kidneys:

Water in the blood is filtered by the kidneys. The two parts of the kidney are the cortex and medulla. The medulla is inside and the cortex is on the outside of the brain. The structural and operational components of the kidney are called nephrons. Nephrons play a critical role in the transfer of waste from your blood to your urine by assisting in the filtering of waste. The majority of each nephron is housed in the medulla. The osmotic concentration outside the medulla is higher than inside the nephron. The process going on here is osmosis. A semipermeable membrane transports water from the nephron tubes to the medulla. The nephron eventually retains concentrated urine. urine goes from the ureter to the bladder.

2. Mangoes shrivel:

Osmosis occurs when a raw mango is immersed in a concentrated salt solution. It shrivels and turns into pickles. Water flows from a lower concentration solution to a higher concentration solution.

3. Transport in plants:

Water travels from the roots to various parts of the plant where it is absorbed by the plant's roots. Water molecules can move from a high concentration (soil) to a low concentration (plant) kudos to each root's function as a semipermeable barrier (roots). Hair on the roots increases surface area and thus the plants' ability to absorb water.

4. Wrinkled fingers:

Our fingers wrinkled when we sat in the tub or immersed them in water for a longer duration. As a result of osmosis. Our fingertips skin absorbs water, expands, and bloats, giving us pruned or wrinkled fingers as a result.

5. Preserving foods:

Osmosis is the cause of the pickles' and jams' ability to be consumed for longer periods of time without going bad. Over the years, both kids and adults have used pickles and jam as quick spreads and ready-to-eat foods. They both have significant amounts of salt and sugar, which serve as organic preservatives for fruits and vegetables. Despite the fact that fruits and vegetables are highly susceptible to bacterial attack, the high salt and sugar concentration is hypertonic to bacterial cells, causing them to lose water and eventually die by dehydration before the food can become spoiled.

6. Soaking dry fruits in water:

When soaked in water, dry fruits swell as a result of osmosis. Until it reaches equilibrium, which happens when the concentrations of both solutions are equal, water moves by osmosis from a region with a higher water concentration to a region with a lower water concentration (resins).

7. Killing slugs and snails:

You've probably heard that pouring salt on a snail or slug will kill it. Well, the only thing that kills them is the osmosis process. They shed water because the liquid inside them leaks out in an effort to reduce the salt concentration and maintain the mucus layer. Slugs and snails will dry up and die if they consume too much salt.

Practice problems:

Q.1. At the osmotic pressure of a solution of potassium nitrate is . Determine the van't Hoff factor.

Solution:

Q.2. Find the osmotic pressure of an urea solution at ?

Solution: Given that

Molarity (C)

Temperature (T)

Q.3. A solution of sodium chloride is isotonic with solution of glucose. Calculate the van’t Hoff factor of sodium chloride?

Solution:

Where Van’t hoff factor of

concentration of

Van’t hoff factor of glucose

concentration of glucose

Q.4. Hypertonic solutions are having

(A) Higher osmotic pressure in comparison to another solution

(B) lower osmotic pressure in comparison to another solution

(C) Equal osmotic pressure in comparison to another solution

(D) None of the above

Answer: (A)

Solution: Isotonic solutions are two solutions that have the same osmotic pressure.

A hypertonic solution is one that has a higher osmotic pressure in comparison to another solution.

A hypotonic solution is one that has a lower osmotic pressure in comparison to another solution.

Frequently asked questions(FAQs):

Q1. Why does osmosis employ passive transport?

Answer: Osmosis and diffusion, respectively, balance the concentration of two solutions. Osmosis and diffusion are both passive transport processes, meaning they don't require extra energy to function. Through osmosis and diffusion, particles move from a region of higher concentration to one of lower concentration.

Q2. Give the reasons why osmotic pressure is a colligative property?

Answer: Colligative property is proportional to the number of solute particles present in the solution, regardless of their nature. Osmotic pressure is proportional to the number of particles of solute, i.e. the molarity of the solute. As a result, osmotic pressure is a colligative property.

Q3. What is reverse osmosis?

Answer: It can be characterized as a separation procedure that forces a solvent through a semipermeable membrane while retaining the solute on one side of the membrane. The solvent is compelled to move from a region of high solute concentration to a region of low solute concentration using pressure. So, it is possible to think of reverse osmosis as the opposite of general osmosis.

By applying pressure and forcing water through a semipermeable membrane, it is used to remove significant contaminants from water.

Q4. What are the different types of semi-permeable membranes?

Answer: A semipermeable membrane is a selective barrier with microscopic pores that only permits the passage of small solvent molecules while blocking the passage of large solute molecules.

Animal leather, or so-called semi permeable membrane, was initially used as the partially allowing semi permeable substance. However, it can be either natural polymers made from plants or animals or synthetic polymers.

Natural semi permeable membrane: Membranes found beneath the outer skin of animals and plants, respectively, make up the natural semi-permeable membrane.

Synthetic or artificial semi permeable membrane: Parchment paper, cellophane, and recently created inorganic substances like copper ferrocyanide supported by porous pot walls are examples of artificial or synthetic semi-permeable membranes.

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