osmosis potato lab experiment

Potato Osmosis Lab

Explore what happens to potatoes when you put them in a concentration of salt water and then pure water. Set up an osmosis potato lab and learn all about osmosis when you try this fun potato experiment with the kids. We are always searching for simple science experiments . Grab the free printable experiment below.

💡 What is Osmosis ? Learn more about osmosis through a variety of experiments.

Recommended Grade Level: 6th-8th Grades

• 2 tall glasses of distilled water (or regular)
• Free printable instructions (below)

INSTRUCTIONS:

STEP 1: Peel and then cut your potato into four equal pieces about 4 inches long and 1 inch wide.

STEP 2: Fill your glasses half way with distilled water, or regular water if no distilled is available.

STEP 3: Now mix 3 tablespoons of salt into one of the glasses and stir.

STEP 4: Place two pieces of potato into each glass and wait. Compare the potatoes after 30 minutes and then again after 12 hours.

What happened to the potato pieces? Here you can see how a potato can demonstrate the process of osmosis. Make sure to go back and read all about osmosis!

If you thought the salt water would have a higher concentration of solutes than the potato, and the distilled water would have a lower concentration you would be correct. The potato in the salt water shrinks because water moves from the potato into the more concentrated salt water.

In contrast, water moves from the less concentrated distilled water into the potato causing it to expand.

What Happens to a Potato in Salt Water?

The process of moving water across a semi-permeable membrane from a low concentrated solution to a high concentrated solution is called osmosis . A semi-permeable membrane is a thin sheet of tissue or layer of cells acting as a wall that allows only some molecules to pass through.

In plants, water enters the roots by osmosis. The plants have a higher concentration of solutes in their roots than in the soil. This causes water to move into the roots. The water then travels up the roots to the rest of the plant.

ALSO CHECK OUT: How Water Travels Through A Plant

Osmosis works in both directions. If you put a plant into water with a higher salt concentration than the concentration inside its cells, water will move out of the plant. If this happens then the plant shrinks and will eventually die.

Potatoes are a great way to demonstrate the process of osmosis in our potato osmosis experiment below. Discuss whether you think the potato or the water in each glass will have the greatest concentration of solutes (salt).

Which potato pieces do you think will expand and which will shrink in size as the water moves from a low concentration to a high concentration?

CLICK HERE TO GET YOUR FREE POTATO OSMOSIS EXPERIMENT!

More Osmosis Experiment Ideas

don’t stop with a potato osmosis lab; try one of these osmosis experiments to extend the learning.

• Rubber Egg Science
• Glowing Spinach
• Growing Gummy Bears
• Colored Celery Science

MORE FUN EXPERIMENTS TO TRY

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Study of Osmosis by Potato Osmometer

A study of osmosis can be done using a potato osmometer. Osmosis is a phenomenon in which water moves from high solvent to low solvent concentration. The movement of water occurs between two compartments, separated by a semipermeable membrane .

The cell membrane of living organisms behaves as a semipermeable or selective membrane. The permeability of a selective membrane differs based on the size, charge and mass of different molecules.

Biological membranes are impermeable to large biomolecules and polar molecules like ions. But, non-polar molecules (lipids) and small molecules (oxygen, carbon dioxide etc.) can cross the selective barrier.

Water is the solvent that travels down or up the cell concentration gradient through osmosis. We can study water diffusion by creating two compartments and a semipermeable membrane in between.

The difference in the concentration of solutes or solvents between two compartments is the driving force responsible for water movement. Here, we need to note that only solvents can pass the selective barrier, not solutes.

Thus, the diffusion or distribution of water is related to osmosis . This post describes the meaning, requirements, procedure and results of the potato osmometer experiment.

Content: Study of Osmosis by Potato Osmometer

Potato osmometer, materials required, precautions.

It is a common experiment to demonstrate both endosmosis and exosmosis using a potato. Using a potato Osmoscope, we can study osmosis in a living system.

Here, a potato is used because the porous outer surface of the potato acts as a selective membrane .

• The contents within the cell form one compartment.
• The solution surrounding the cell forms another compartment.

Thus, a selective membrane separates two compartments and allows the process of osmosis .

• High solvent concentration in the cell surrounding.
• Low solvent concentration in the cavity of potato tuber.

Following the rule of osmosis, water in the cell surrounding enters the tuber cavity via the cell membrane.

• High solvent concentration in the cavity of potato tuber.
• Low solvent concentration in the cell surrounding.

Following the rule of osmosis, water in the potato cavity enters the surrounding solution via the cell membrane.

• Peeled off potato
• Concentrated sugar solution
• Petri plate

Video: Study of Osmosis

To perform the potato osmometer experiment, we need to follow the given procedure:

• First, peel off the large-sized potato using a peeler or knife.
• Then cut the upper and lower portions of the peeled potato using a knife. Through this step, we can easily place the potato on the Petri plate.
• Using a knife, make a cavity from the centre of the potato deep into the bottom, leaving some space. Here, the bottom of the potato will function as a selective membrane.
• Then, keep the potato on the Petri plate.
• To study endosmosis , pour water into half of the Petri plate. Next, pour the concentrated sugar solution into half of the cavity created in the potato.
• To study exosmosis , add concentrated sugar solution on the Petri plate and water into the cavity of the potato tuber.
• Then, fix a pin into the potato tuber-A and B to mark the level of sugar solution and water added into the cavity.
• Leave the plate undisturbed for some time until you notice any change.

Observation

• Observe the level of sugar solution in the cavity of potato tuber-A.
• Notice the level of water in the cavity of the potato tuber-B.

Potato Osmosis Experiment Results

• The level of sugar solution in the cavity of potato tuber-A increases . It occurs because the water in the Petri plate will move towards the cell with a high solute or low solvent concentration. This experiment shows endosmosis , as water goes into the cell or potato tuber.
• In contrast, the level of water in the cavity of potato tuber-B decreases . Here, water in the cavity moves toward the solution in the Petri plate due to the high solute concentration in the surrounding. This experiment shows exosmosis as water leaves the cell or potato tuber.
• The cavity should be deep enough by leaving a minimum thickness at the bottom.
• The sugar solution should have a high osmotic concentration.

The water movement from the Petri plate to the potato cavity or vice versa is due to the difference in the solvent or solute concentration between the two compartments.

Related Topics:

• Germination of Plant
• Difference Between Root and Stem
• Nerve Impulse
• Ozone Formation
• Examples of Adsorption in Daily Life

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