Osmosis Experiment: Seeing Osmosis in Action (with video!)

Easy Osmosis Experiment for nursing students

What is Osmosis?

Before we do an osmosis experiment, let’s first understand what osmosis is. Osmosis is the movement of water through a semi-permeable membrane see the .  During osmosis, the water moves from an area of low-concentration (i.e. where there’s only a little bit of solute) to an area of high-concentration (i.e. where a lot of solute is present).

That means that there are 2 key points to remember about Osmosis:

  1. It’s the movement of water.
  2. It requires a semi-permeable membrane.

One way you can think about this concept is that the water is trying to dilute whatever is nearby, and that there is some sort of barrier (the semi-permeable membrane) between the water and the “stuff” being diluted. The water has to be able to move through the barrier, but not the particles being diluted.

Osmosis vs Diffusion

Osmosis can be easily confused with Diffusion, especially when you are beginning your nursing studies (or if it’s been a while since you’ve studied Anatomy & Physiology!).

Unlike Osmosis, which is the movement of water through a semi-permeable membrane, diffusion is the movement of particles (solute) and doesn’t necessarily involve a semi-permeable membrane

(Need a quick review about what solute, solvents, and solutions are?).

One of the main reasons that these two processes are frequently confused is because they are often happening simultaneously in the human body. Osmosis and Diffusion are both essential processes in the body that work together to help maintain homeostasis.

Osmosis Experiment

One of the reasons why it’s really difficult to understand complex processes occurring in the human body is because they are invisible to the naked eye. I can’t see my blood flowing through my veins and arteries, and I can’t see how the processes of osmosis and diffusion effect that blood flow. I certainly can’t see the electrolytes that are dissolved into my blood!

That is why I believe it’s sooo much easier for nursing students to understand these concepts when we can actually SEE a real life example in action! So here’s an osmosis experiment I developed that shows the effects of hypertonic, isotonic, and hypotonic fluids on eggs. (Spoiler alert: I broke an egg! 🤦‍♀️)

(Scroll past the video for more examples of osmosis, as as well as instructions on how to do this experiment for yourself!)

How to Do Your Own Osmosis Experiment at Home

So how can you do this Osmosis Experiment for yourself? Here’s the simple plan (with some explanations of what I would do differently next time!)

Supplies

Make sure you have on-hand:

  • 3-4 eggs of similar size (use 4 if you’re klutzy like me and might break one!)
  • 3 containers (one for each egg)
  • White vinegar (enough to cover all the eggs)
  • 3 Testing Fluids:
    • Isotonic (Saline solution, or make your own 0.9% saline solution by mixing salt and distilled water)
    • Hypotonic (I used tap water, but if I did it again I would use distilled water instead)
    • Hypertonic (I used high-fructose corn syrup)
  • A towel…just in case you break an egg, too 😉

Step 1: Dissolving the egg shells

Side note: Dissolving egg shells in vinegar is way fun, and worth doing even if you don’t plan on trying the rest of the experiment. Squishy raw eggs are way cool. Just don’t try to bounce them. You’ve been warned 😂

In order to get your semi-permeable membrane, you need to remove the egg shells without breaking the delicate membrane underneath. The best way I’ve found to do this is by soaking them in vinegar. Simply put all the eggs in a container together, cover them with vinegar, and wait. 

For the osmosis experiment in the video, I left the eggs in the vinegar for several days after the shells had dissolved. After seeing the final results, I realized that vinegar acts as a hypotonic solution to the eggs, which means that the eggs probably absorbed quite a bit of water before I even started the “official” osmosis experiment.

Next time, I would check on my eggs more frequently, and pull them out of the vinegar solution as soon as the egg shell has dissolved.

Step 2: Applying the hypertonic, hypotonic, and isotonic solutions

Place each egg in its own, individual container. Label each container with the solution you will be adding. Then pour each solution into the container until the egg is completely covered:

  1. Isotonic (saline solution)
  2. Hypotonic (distilled water)
  3. Hypertonic (high-fructose corn syrup)

This part of the experiment is definitely not time sensitive. Once osmosis has caused as much water movement as is possible for this set-up, it will stop and wait patiently until you have time to check it 🙂

Step 3: Evaluate your results

Fluids and Electrolytes are hard for nursing students to understand because they are usually hard to visualize. This experiment shows you exactly what can happen to red blood cells when you administer isotonic, hypotonic, and hypertonic solutions.

Remove the eggs from their solutions and compare their sizes. Did you get the same results that I did? Did the egg from your hypertonic solution shrink? Did your egg in the hypotonic solution get fatter? Is your egg from the isotonic solution still look normal egg sized?

Now let’s apply these results to nursing school. Think about the different IV solutions we use in the body. What if that egg had been a red blood cell?  What would happen to a patient who got too much hypertonic IV solution?

Osmosis is a real phenomenon that has real consequences for our nursing practice, so it’s important to make sure you understand what’s going on at the molecular level.

Osmosis Examples

Osmosis doesn’t only happen in our bodies (or only in eggs, for that matter). It also happens all around us everyday! Here’s some examples of osmosis in action, both inside AND outside of the body

Kidneys

The kidneys filter our blood and make urine. It’s a pretty complex process that involves many moving parts, but two of the major processes are osmosis and diffusion. This is a perfect example of how they work together in the human body.

Salting a Slug

The cells of slimy slugs contain a relatively large amount of water. If you were to sprinkle salt onto a slug, that water would start exiting the cells in an attempt to “dilute” the salt. If enough salt is applied, then the slug will get extremely dehydrated and die. Eww.

Pruned and Wrinkly Fingers

Ever noticed how wrinkly your fingers and toes can get after you’ve been soaking in the pool or the bathtub for too long? That’s osmosis! The water in pools and tap water generally has a lower concentration of solute than our skin cells do. This causes the water around us to try and dilute the solute in our skin.

So the next time you notice your wrinkly skin after a bath, you’ll know it’s because your carrying some of the bath water in your skin cells!

Salting Vegetables

You can easily do another osmosis experiment while you’re cooking! Some recipes call for dicing, salting, and resting your veggies before cooking. When you do this, you’ll find that the salt triggers the process of osmosis. Just like the example with the slug, water from inside your veggies will start exiting in an attempt to “dilute” the salt on the surface.

Not only is this a fun experiment, but it can concentrate the flavors of your vegetables and make the final dish less watery.

Hypernatremia

When you have too many sodium ions in your blood vessels, then the water in your body will work to bring you back to homeostasis. The water can move into your blood vessels from the interstitial space, or even from your red blood cells! A little bit of movement is totally normal, but as you can imagine, you don’t want a ton of water leaving your red blood cells or they will quickly end up looking like a salted slug!!

There are many, many more examples of osmosis all around us. Share your ideas in the comments below!

(Article updated 7/21/2018, Originally published 6/26/2012)

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33 Comments

  1. I really liked this article. However, I am still unclear as to how osmosis really works. What causes the water containing little solutes to move into an area of higher concentration? Does it have to do with some form of magnetic attraction between negative and positive charges? Is there less pressure inside an RBC compared to the inside? I would like to learn more about this. Also, how does one calculate the tonicity of saline to insure that it is safe to inject, such as those used in simulations? I am guessing that one should not make normal home-made saline, as it would not be sterile, yet I’d like to see a solution having a good salinity with no additives or preservatives.

  2. Yani

    LOL on the first egg… LOVE you video.. went thru LPN school and now in Med-Surge for RN… I FINALLY understand the concept.. THANK YOU… I will def follow u

  3. Delana Rhodes

    Thank you so much, I have been struggling with the idea of osmosis and the different solutions but your visual helped to make it clear for me!

  4. Stina Haener

    Thank You! That was just what I needed to completely understand this concept. I am just about done with the prerequisites for the RN program and will apply in the fall. I will continue to use your great website for tutoring! 🙂

  5. Muddassir

    Thankyou. It is very informative and helpful to understand the process of Osmosis as well as the action of hoypotonic,hypertonic and isotonoic solution. Its a practical example which help to understand easily for weak students like me….. 🙂

  6. Dina E.

    Studying this in Med-Surg. After having seen your experiment I have a bigger understanding of it, seeing that hypertonic can be danger when trying to balance the water within the body/blood vessels causing RBC TO BECOME DEHYDRATED.

  7. Deborah

    Great experiment. Love your site. I run at 100mph all the time and never take the time to tell you that your tutorials are very useful and I enjoy perusing this site. Darling kids too, just love those sweet babies!
    Bless you, Deborah

  8. sofia

    Thank you for the video demonstration it really helped for me to understand the concept of the different types of IV solutions.

  9. Deb

    Nicole,
    I am going to teach an IV class at work and I was looking to clear up isotonic, hypotonic, and hypertonic solutions in my own mind and I am glad I found your site, Osmosis and the differences between the soulutions can be very confusing, This helped me to understand better than anything I have ever read.

    • It can definitely be confusing. Even I have to pause sometimes and think it through again in my own mind each time I teach it! Have fun teaching your IV class!

  10. Graxia

    You’re so pretty and smart, you have thought to do that. Thanks for sharing and I could see the zeal in your heart to nursing and hope you won’t get tired sharing your unique skill and knowledge. Wish to be like you 🙂 more power!

    • There are multiple types of pressure interacting that influence which direction the water flows: oncotic pressure, osmotic pressure, and even just water pressure. When the forces pushing water IN are equal to the forces pushing it OUT, then the water will stop flowing and stay where it is unless something changes.

  11. Bridget

    You are an angel . Finals this week and I have not getten this all semester .
    Thank you so much !!!
    How do I follow your post I want more helpful info?

    Thanks again

    • Hi Bridget,
      So glad I could help!
      The best way to follow my posts is to sign-up for the email newsletter, which you can do by entering your name and email in the sign-up box to the right of the webpage.
      Good luck with finals! Let me know how they go for you!

  12. Lisa

    Thanks for the video, great experiment, and great rationale behind why the isotonic and hypotonic solutions didn’t show that much of a change compared to the egg in the hypertonic solution! This would have been a great vid while I was in nursing school – but I’m still glad that I found it now! 🙂

  13. Erin

    hi there, loved the experiment. i was trying to find the answer to this: A hypertonic solution is likely to contain … many / no electrolytes?
    and stumbled across your page. i’ll be saving this im my favs. I have just started my Bachelor of nursing and hope to do my post grad in midwifery.
    please feel free to explain if a hypertonic solution contains electrolytes.
    Cheers, Erin

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