egg in salt water experiment results

Enjoy fun science experiments for kids that feature awesome hands-on projects and activities that help bring the exciting world of science to life.

Make an Egg Float in Salt Water

An egg sinks to the bottom if you drop it into a glass of ordinary drinking water but what happens if you add salt? The results are very interesting and can teach you some fun facts about density.

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How salty does the sea have to be for an egg to float.

Try this eggs-periment to learn why some objects float in the ocean while others sink

Which glass holds the salty water? This activity will help you figure it out.

Arthit Pornpikanet/iStock/Getty Images Plus

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By Science Buddies

January 24, 2023 at 6:30 am

Objective : Determine what salt concentration will float an egg

Areas of science : Ocean sciences

Difficulty : Intermediate/Easy

Time required : ≤ 1 day

Prerequisites : None

Material availability : Readily available

Cost : Very low (under $20)

Safety : Always wash your hands after handling uncooked eggs because they may carry  Salmonella .

Credits : Andrew Olson, PhD, Science Buddies; Sandra Slutz, PhD, Science Buddies

Did you know that if you put an egg in a cup of tap water, it will sink to the bottom? But, if you add enough salt, the egg will float back up to the surface! Why? Because the density of the egg is higher than the density of tap water, so it sinks. 

Density (ρ),  as shown in Equation 1, is the  mass (m)  of a material per unit  volume (v).  For example, the density of freshwater under standard conditions is approximately 1 gram (g) per cubic centimeter (cm 3 ). In other words, if you filled a 1-cm x 1-cm x 1-cm box with freshwater, the water inside the box would have a mass of 1 g.

Adding salt to the water increases the density of the water, because the salt increases the mass without changing the volume very much. With enough added salt, the saltwater solution density is higher than the egg’s, and the egg will then float, as shown in Figure 1. The ability of something, like the egg, to float in water or some other liquid is known as  buoyancy .

Equation 1:

ρ  = Density in whatever units are used for mass and volume. m  = Mass in grams (g), kilograms (kg), or any other unit of weight. v  = Volume in centimeters cubed (cm 3 ), meters cubed (m 3 ), or any other unit of volume.

But just how much salt is needed to make an egg float? In this science fair project, you will figure that out by placing an egg in cups with different salt  concentrations . The concentration of a solution tells you how much of a compound is in a certain volume of a mixture.

In chemistry, the  mass concentration  is one way of expressing the concentration of a solution. The mass concentration is defined as the mass of a compound (in grams) in a certain solvent volume (in liters) and has the unit grams per liter (g/L). For example, in a solution with 750 grams of salt (sodium chloride or NaCl) in 1.5 liters of water, the mass concentration of salt is 750 g/1.5 L = 500 g/L.

In this project, you will be using the technique of making serial dilutions to create solutions with different salt concentrations. A  serial dilution  is a method for accurately diluting a solution in regular steps. You add a known amount of your starting, or  stock,  solution to a known amount of water and mix them. This process is called dilution. Diluting a solution means adding additional solvent (water in this project) to decrease the solution’s concentration. The new concentration of the diluted solution can be calculated using Equation 2.

Equation 2:

Here is an example calculation. Let’s say you have a salt solution with a mass concentration of 500 g/L. You dilute this solution by mixing 0.25 L of that salt solution with 0.25 L of water. This brings the total volume of your dilution to 0.5 liters (0.25 L + 0.25 L). To calculate the mass concentration of salt in the diluted salt solution you use Equation 2:

Solving the equation tells you that your dilution has a salt concentration of 250 g/L, which is half of your stock solution.

As a general rule, if the volume of stock solution and the volume of solvent (water) for your dilution are equal, you will be diluting the solution by half. This is called a  two-fold  dilution. A two-fold dilution means that with each dilution step, the new concentration of the dilution should be 50 percent of the original concentration.

If you want bigger steps, you should use relatively more water; if you want smaller steps, you should use relatively less water. By repeating the process, you can make a whole series of dilutions, which is how the method got its name. In this ocean science project, you will start out using two-fold dilutions to find out how much salt will cause an egg to float.

Terms and concepts

• Serial dilution
• Mass concentration
• Relative concentration
• Absolute concentration
• Why would an egg float in water with a lot of salt in it, but not in plain tap water?
• What happens to salt (sodium chloride or NaCl) molecules when dissolved in water?
• Why does adding salt to water increase its density?

Materials and equipment

• Permanent marker
• Table salt (1 cup)
• Measuring cup, liquid
• Large container, such as a large bowl or cooking pot. Must be able to hold at least five cups.
• Spoon for stirring
• Bag of clear 16-oz plastic cups
• Soup spoon for egg transfer
• Lab notebook

Experimental Procedure 

• Science Made Simple, Inc. (n.d.).  Metric conversions & US customary unit conversion calculator .  Retrieved April 15, 2013.
• Take five eggs out of the refrigerator, use a permanent marker to label them 1-5, and allow them to warm to room temperature.
• Pour 3 cups of water into your large container.
• Add 1 cup of salt.
• Stir to dissolve some of the salt. It will not all dissolve yet.
• Add 2 more cups of water.
• This may take several (5 to 10) minutes of stirring, so you may need to be patient.
• Label five of the plastic cups 1-5. Cup 1 will be for the stock solution, cups 2-4 will be for the dilutions, and Cup 5 will be plain tap water.
• Add 3/4 cup of your stock salt solution to Cup 1.
• Add 3/4 cup plain tap water to cups 2-5.
• Measure out 3/4 cup stock solution, and add it to Cup 2. Mix.
• Measure out 3/4 cup of the solution from Cup 2 and add it to Cup 3. Mix.
• Measure out 3/4 cup of the solution from Cup 3 and add it to Cup 4. Mix.
• What are the  absolute mass concentrations  of salt in cups 1-4? (To calculate with metric units, use these conversions: 1 cup of salt is 292 grams [g], 1 cup of water is 237 milliliters [mL], and 3/4 cup of stock solution is 177.75 milliliters [mL]). Write these concentrations down in your lab notebook. Review the Introduction section if you need help with your calculations.
• What are the  relative salt concentrations  in cups 2-4 compared to the original stock solution? Use the absolute mass concentrations that you calculated in the previous step for your calculations.  Example : Let’s assume that the original stock solution in Cup 1 has a salt concentration of 500 g/L. Cup 3 has a salt concentration of 125 g/L. The relative salt concentration can be calculated as the ratio of 125 g/L / 500 g/L, which is 0.25. Expressed as a percentage, this would be 25%. Therefore, Cup 3 has a relative salt concentration of 25% compared to Cup 1.
• Now, starting with Cup 5 and working your way up, test an egg in each solution to see if it will float. Use a soup spoon to lift the egg in and out of the cups.
• Be sure to record your results and observations in your lab notebook, including the egg’s number.
• Repeat steps 5-6 with four other eggs.
• Now you know, within a factor of 2, how much salt it takes to float an egg. How can you narrow down the range further to get a more precise estimate? By doing another serial dilution, of course.
• Figure out a new serial dilution with smaller steps. For example, you could try diluting the solution by 25 percent with each step. That means with each step, the new concentration should be 75 percent of the original concentration.
• Remember that you will need enough solution to more than cover the egg, which will probably be around 3/4 cup, and you probably cannot fit more than 2 cups of solution in each 16-oz cup.
• Hint:  You may only be able to test the first few cups in a dilution series at a time unless you use larger cups.
• Tip:  If you need additional help for making serial dilutions, check out the serial dilutions resource in the Bibliography in the Background section.
• Write up your new dilution procedure in your lab notebook, including the calculated relative and absolute salt concentrations for each cup.
• Make the new dilution series. Remember to start with the salt concentration where the egg first floated. (If you do not have enough solution from the original serial dilution, make some more by starting from the stock solution.)
• Repeat this step with the four other eggs.
• When you are done handling the eggs, wash your hands with soap and warm water. It is important to wash your hands after handling uncooked eggs because they may carry  Salmonella .
• Hint:  If the density of the saltwater is less than the egg’s density, the egg will sink, and if the density of the saltwater is greater than the egg’s density, the egg will float. So the density of the egg would be between these two absolute salt densities.
• Plot the densities for all five eggs on a chart, putting the egg’s number on the x-axis and its density on the y-axis. What is the density of the eggs? How much variation in density is there from egg to egg?
• Does a hard-boiled egg float at the same salt concentration as an uncooked one? Hint: You will need to measure the same egg before and after hard boiling and be very precise about your serial dilutions.
• Find out how much salt there is in sea water. From the results of your experiment, predict whether an egg would float or sink in sea water. (If you live close enough to the ocean, you can get collect some sea water and test your prediction!)
• Figure out another method of determining the density of an egg. Compare the density measurements for the same eggs using your method and this salt water float test.

This activity is brought to you in partnership with  Science Buddies . Find the original activity on the Science Buddies website.

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Salt Water Density Experiment

Can you make a fresh egg float in water? What will happen to an egg in a saturated solution of salt water? Will an egg float or sink in salt water? What is density? What is buoyancy? There are many questions and hypotheses (predictions) to make with this easy salt water experiment, and you can learn about it all with just water, salt, and eggs! Check out all our classic science experiments for more great ideas!

SALT WATER DENSITY EXPERIMENT

Let’s get ready to investigate! Head to the kitchen, open the pantry, and be prepared to get a little salty. And if you are curious about the rubber egg experiment in the video, click here .

YOU WILL NEED:

• 2 Tall glasses big enough to hold an egg

SALT WATER EXPERIMENT SET UP:

STEP 1:  Start by filling one glass about 2/3 of the way full with water. Ask the kids what will happen if you carefully drop an egg into the glass of water. Now go ahead and do it!

STEP 2:  In the other glass, fill to the same height with water. Now stir in 3 tablespoons of salt. Mix well to dissolve the salt! Ask the kids what they think will happen this time and demonstrate!

TIP: Now’s a great time to talk about mixtures. By combining salt and water, you are making a mixture, an important science concept ( Grab a free printable list of science words )!

A mixture is a material made up of two or more substances mixed together. No chemical reaction takes place, and you can separate the substances in the mixture. You can have a mixture of liquids, solids, or gases.

The second egg should float due to the water’s density change!

SALT WATER DENSITY IN THE CLASSROOM

Kids can easily experiment with different objects from around the room. Small plastic items will work best with the measurements of salt and water provided.

If the item still sinks in the salt water, ask the kids what they think! Should they add more salt? Have each kid contribute an item to the experiment!

This is a great experiment to add to your ocean science lesson plans because the ocean is salty!

So many great saltwater density questions:

• Do you float better in salt water?
• What about some of the biggest mammals on earth that float easily in the ocean?
• Does the density of the saltwater play a role?

Why is the ocean salty? The simple answer is that the salt comes from the rocks on the land that has been broken down by erosion and is carries by streams to the ocean.

WHAT IS DENSITY?

Why do some objects sink while another object floats? An object sinks because it is denser or heavier than water and vice versa. Our sink and float experiment is another exciting way to look at items that might surprise you using only water.

Big items that feel light, like a ping pong ball, are less dense than smaller items that feel heavy, like a gold ring. When added to water, objects denser than water sink, and those less dense than water float. Hollow things often float as air is less dense than water. Learn more about what is density.

You can experiment with many objects that sink and float in water, but what happens when you add salt to the water? Can you change whether the object, like the egg, still sinks?

How does salt affect the density of water?

Adding salt to water densifies it. As the salt dissolves in the water, it adds mass (more weight to the water). This densifies the water and allows more objects to float on the surface that would sink in fresh water. This is an example of a physical change !

Do objects float better in saltwater or freshwater?

What other items can you find to test? Most items will generally float in this salt water experiment even if they sink in freshwater. Just look at the egg!

CHECK OUT MORE SIMPLE SCIENCE IDEAS

• Sink the Boat Buoyancy Challenge
• Freezing Point of Water
• Frost on a Can (not just for winter!)
• Sink or Float Experiment
• Do Oranges Sink or Float?
• What Dissolves in Water?

Turn It Into A Science Fair Project

Science projects are an excellent way for older kids to show what they know about science. They can also be used in all sorts of environments, including classrooms and groups.

Kids can take everything they have learned about using the scientific method , stating a hypothesis, choosing variables , making observations , and analyzing and presenting data.

Want to turn one of these experiments into an awesome science fair project? Check out these helpful resources.

• Science Project Tips From A Teacher
• Science Fair Board Ideas
• Easy Science Fair Projects

Helpful Science Resources To Get You Started

Here are a few resources that will help you introduce science more effectively to your kiddos or students and feel confident yourself when presenting materials. You’ll find helpful free printables throughout.

• Best Science Practices (as it relates to the scientific method)
• Science Vocabulary
• 8 Science Books for Kids
• All About Scientists
• Free Science Worksheets
• Science Supplies List
• Science Tools for Kids
• Scientific Method for Kids
• Citizen Science Guide
• Join us in the Club

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
• Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

15 Comments

When I click the link to go to your blog from my email, a virus (weird website) keeps popping up. I like your blog. But you may want to check into the virus.

I think Liam’s explanation of water density is perfect – smart kid! These projects are a perfect way to *show* kids the difference, instead of just trying to explain it to them (like you said, nearly impossibly for preschoolers!)

I can see salt water being a big hit around here for experimenting! This looks so fun! Pinning for the future!

Lots of stirring but lots of interesting fun! Thanks for pinning!

Thanks Emma! He’s a smart cookie and likes to see things too understand! Not big on listening a whole bunch just yet 😉

Thanks I will look and see what I can see! Glad you like it!

Very good post. I absolutely love this site. Continue the good work!

I like this experiment but it is not about weight it is about density.

Yes, I have been meaning to update it a bit more. Thank you.

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Science project, floating eggs: a pre-breakfast experiment.

Before you get ready for a delicious scramble or omelet, add a bit of science to your morning routine! Do you know why some things float and other things don't? In this experiment, you'll use eggs (and a few scoops of salt) to study the science of floating.

Will an egg float better in salt water or fresh water?

• 2 clear containers
• Measuring spoons
• Stirring spoon
• To begin your floating eggs experiment, fill your two containers with water. Make sure the amounts are equal. When you're doing a comparing experiment like this, all the variables , or factors that make up the project, should be the same -- except one (in this case, salt water instead of fresh water).
• Use the measuring spoons to pour seven tablespoons of salt in the first container of water. Do not put any salt in the second container.
• Stir the container of water until the salt is completely dissolved. This may take a couple of minutes.
• Gently place one raw egg in each container.
• Watch the eggs for a few seconds. What happens?

The egg should float in salt water, but not in fresh water.

The key to this experiment is density . Density deals with how closely packed together a substance is. You can see density in your food. Imagine you have two bowls that are the same size. In one bowl, you have a salad, but the other one is full of a pot pie. Even though each bowl is filled with food, the pot pie is much denser because the ingredients are smooshed closer together than a light salad of lettuce and just a few vegetables.

In the same way, salt water is denser than fresh water. The molecules are packed tighter, and this density allows an egg to float on the water's surface. Remember that eggs have density too, but because an egg's density is less than salt water's density, you saw floating eggs. On the other hand, an egg is denser than fresh water -- that's why it sunk to the bottom of the container.

Equipped with just a bowl of salt water and a bowl of fresh water, you can test the density of all sorts of ingredients in your kitchen. Do you think a mushroom would float in both liquids? What about a block of cheese? You can even bring out the eggs again -- what do you think would happen if you tried a hard boiled egg instead of a raw one? Keep guessing and testing like a real scientist!

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How Does Salt Water Make an Egg Float?

How to Float an Egg in Water

Demonstration.

Fill two clear glasses with lukewarm water. Pour 1 tablespoon of salt into one glass, and stir until the salt dissolves. Gently drop a fresh egg into the plain water. The egg will sink to the bottom. Remove the egg and place it in the saltwater. The egg will float.

How It Works

Objects sink in liquids when their density is greater than that of the liquid. Conversely, objects float when the density of the liquid is greater than that of the object. An egg has greater density than plain water, so it sinks. Salt increases the density of water, however. The denser the water, the easier it is for an egg or other object to float.

More About Density

The higher the salt content of water, the higher an object will float. If you add less than 1 tablespoon of salt to a glass of water, it is possible to make the egg float in the middle. This also can be accomplished by adding 1 tablespoon of salt to water and not stirring. Because the salt is denser than the water, the salt will sink. When you drop the egg into the water, it will sink through the plain water until it reaches the saltwater at the bottom of the glass. The density of the saltwater prevents the egg from sinking any lower, so the egg will float in the middle of the glass.

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• Science Buddies: How Salty Does the Sea Have to Be for an Egg to Float?
• Science Kids: Experiments - Floating Eggs

About the Author

Angela Powell Watson has written for dozens of print and online resources, and recently published her first book. Watson holds a Bachelor's degree in Early Childhood Education and Art from Hood College, a Master's degree in Curriculum and Instruction from Western Maryland College and National Board Certification as an Early Childhood Generalist.

Photo Credits

Steve Baccon/Photodisc/Getty Images

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Floating Egg Experiment

This floating egg experiment is a lot of fun for kids to try! You can get an egg to float in the middle of the glass and it’s almost like a magic trick! You only need eggs, salt and water. Kids can learn about density with this cool science experiment!

RELATED: Dancing Corn Experiment

Floating Egg Science Experiment

Have you ever made an object float? How about when you go swimming in salt water, do you notice you float much more easily?

This science experiment explores the difference between salt water and fresh water and why objects float in salt water!

Watch the Video Tutorial!

The science.

This is a classic science experiment that shows how changes in the density of a liquid can affect whether an egg sinks or floats.

When you place an egg in regular water, it will sink to the bottom of the glass because the egg is denser than the water. There are more molecules per square inch in the egg than the water, causing the egg to sink.

When you start to add salt to the water, the salt dissolves and the molecules spread out and increase the density of the water. Now there are more molecules per square inch in the water, which causes the egg to float.

Water Only Glass

The egg sinks because it is more dense than fresh water, meaning there are more molecules per square inch.

Salt Water Glass

Adding salt to the water increases its density by adding more molecules per square inch, causing the egg to float. The egg is less dense than the salt water.

Water & Salt Water Glass

When you fill up the glass halfway with the salt water, the egg floats. When fresh water is added on top, it is less dense than the salt water, so it floats on top, allowing the egg to still float in the middle.

The egg continues to float in between the space where the fresh water meets the salt water because the egg is still less dense than the salt water but more dense than the fresh water.

How to do the Floating Egg Experiment

1. Carefully add your eggs into each cup.

You will need 3 eggs.

2. Pour fresh water (cold tap water is fine) into the first cup.

3. Make the salt water.

Boil hot water in a kettle. Adults to assist with this.

Add 1/4 cup of salt into a pouring cup.

Then add about 2 cups of the hot water.

Stir until dissolved and clear.

Add the hot water into the far right cup until the water line matches the first cup. The egg should now float in this cup.

Note: if it does not float, you need to repeat with more salt and try again.

4. Add the salt water into the middle cup.

Fill until halfway up the cup. The egg should still float. If you do not have enough salt water, repeat the step above to make more.

Now pour fresh water on top of the salt water. The egg should now stay in the middle of the cup.

Now you have all three cups showing how eggs can float or sink in water!

See more science experiments about density:

• Dancing Corn Experiment
• Oil & Water Experiment

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Use a giant cell—a de-shelled chicken egg—to explore the comings and goings of cellular substances.

• Several chicken eggs
• Large container, such as a wash basin or large bowl
• Pencil and notepaper (or similar) for recording information
• Several substances in which to soak or bury the de-shelled eggs, such as distilled water, dry salt or saltwater solutions, colored water, corn syrup, rubbing alcohol, cornstarch, or baking soda
• Containers to hold the soaking eggs
• Plastic wrap (not shown)
• Masking tape and marker for labeling containers
• Optional: nitrile or latex gloves for handling eggs, glass jars or other small objects to hold down floating eggs

• Determine the treatments you’ll be using on your eggs, and prepare the substances you’ll need. You can make salt-water solutions by dissolving different amounts of table salt in containers of water (e.g. 100g, 200g, 300g of salt (NaCl) per liter). You can make solutions of food coloring by adding a few drops of each color into containers of water. Remember to label your containers as you work.

Use a scale to find the mass of each de-shelled egg before treatment. Record the result on notepaper.

Place one egg in a labeled container and cover it with your chosen treatment. (If the egg floats, you may use something to hold it down, such as a glass jar; see photo below.) Repeat for each of the remaining treatments. Be sure to set aside an untreated "control" egg. After taking its mass, cover the control egg with plastic wrap, and set it in a container alongside the treatment eggs.

Place the treatment containers somewhere they can sit for at least a day at room temperature. Observe any changes that occur in the eggs during the first hour or so of soaking and record your observations.

Observe any changes in the color, size, or shape of your experimental eggs. Record your observations. Then, gently remove your sample eggs from their treatments to measure and record the mass of each one (see photo below). Remove the plastic wrap from the control egg and measure its mass too. Calculate the percentage change in mass for each egg by dividing the final mass by the starting mass and multiplying by one hundred percent.

In a separate bowl, carefully dissect the egg by piercing the membrane. Record your observations.

How did each egg change? Did its mass increase or decrease? Do you see anything in common with the treatments that enlarged the eggs? Which treatments made the eggs shrink, and which did not?

In general, the most dramatic changes to the mass, color, and shape of the eggs will occur within the first 24 hours of the experiment. Eggs submerged in corn syrup will have lost considerable mass and have the appearance of flabby sacks. Eggs soaked in distilled water will gain mass and appear dramatically swollen. Eggs in dilute salt solutions will gain mass, and even those in very concentrated solutions might gain mass. Eggs buried in salt or other dry media should lose mass.

The de-shelled eggs serve as good models of human cells. After the eggshell is removed, a thin membrane (actually, two membranes held tightly together) remains. This membrane, like those in human cells, is selectively permeable, allowing certain substances to pass through while blocking others.

Substances that can pass easily through the membrane of the egg will follow the principles of diffusion. They will move through the membrane from the side where they are at a higher concentration to the side where they are at a lower concentration (click to enlarge the diagram below). This movement will continue until the concentration on both sides is the same. While random molecular motion will cause individual molecules to continue moving back and forth across the membrane, the overall concentration on each side will remain in equilibrium, with equal concentrations on both sides.

The egg’s membrane is permeable to water. Movement of a solvent (such as water) across a semipermeable membrane from a less concentrated solution to a more concentrated one is called osmosis . When an egg is soaked in a solution that has a higher solute concentration (the relative amount of dissolved stuff) than the solute concentration inside the egg, water moves out of the egg and into the solution (see diagram below).

As a result, the egg loses mass and ends up looking deflated. An egg naturally has a lot of stuff inside, so the outside solution has to be very concentrated for this to happen. That’s the case when an egg is treated with corn syrup or buried in salt. By contrast, when an egg is treated with distilled water, or a dilute salt solution, the solute concentration is higher inside the egg than out, so the water moves into the egg, increasing its mass. It may be easier to think about osmosis in terms of water concentration rather than solute concentration. If the solute concentration is high, then the water concentration will be low by comparison.

Rubbing, or isopropyl, alcohol is at least 70% alcohol and therefore less than 30% water. This should cause water to move from the egg into the solution, and the egg should lose mass. In addition, the egg may appear white and rubbery. Alcohol that diffuses into the egg can denature the proteins, unraveling their three-dimensional structure and causing them to coagulate or join together. Egg proteins turn from translucent to white when they are denatured. In cooking, temperature is used to denature these proteins, but you may have noticed that alcohol has also "cooked" the egg and caused it to look hard-boiled.

The plasma membranes of your cells behave much like those of the egg. All of the trillions of cells in your body are like busy seaports with materials coming in and going out. Water, oxygen, and nutrients must pass through the plasma membrane into your cells, and wastes must leave. When the concentration of oxygen is higher in your lungs than it is in your blood, for example, the oxygen diffuses into red blood cells through capillary walls. Your flowing blood then transports that oxygen to your tissues. From there, the oxygen diffuses into other cells to be used in cellular respiration. Through a similar process, water in the stomach moves into the bloodstream and is then carried to the cells, where it supports a variety of essential bodily functions.

Predict what would happen if you placed the shrunken eggs in plain water overnight. Do the experiment and explain your results.

In this activity, not only can you measure how much material moved into or out of a treated egg, but you can also chemically determine whether molecules moved across the membrane. If you break the egg into a dish, or save some of the soaking solution, you can use chemical tests to see what’s there. For example, you can use Benedict’s solution to test for simple sugars, iodine to test for starch, or Biuret solution to determine whether or not protein exited the egg as it soaked.

When using this activity with large groups of students or multiple classes, have each group apply only one treatment, and then analyze the data collected from all groups. Having each small group design an experiment with one egg will allow you to do the activity with fewer eggs per class, and collecting several sets of data will enable students to identify any outliers.

This Snack is an excellent activity for introducing diffusion, osmosis, and the semipermeability of membranes and allows learners to engage in the NGSS Science and Engineering Practices. By collecting data from multiple classes, you can facilitate a discussion about what and how much data is necessary to count as evidence. Students can also use the evidence about what and how much material moves into and out of the egg to formulate a revisable model about how osmosis occurs and what might prevent or allow molecules to move through membranes. By incorporating related activities, such as the Cellular Soap Opera Snack, students can form a more complete conceptual model of the cell membrane and how molecules move along concentration gradients.

Note that it’s also important to discuss the idea that models such as this one have limitations. There are structural differences between the membranes of chicken eggs and human cells that result in differences in permeability. Some of the molecules that pass through the egg’s membrane in this activity would not pass through a human cell membrane because of their size (such as cornstarch) or their charge (such as Na + and Cl - from the salt). 

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Floating Egg Experiment

What happens when you toss a coin in water? It sinks, doesn’t it? But why does an apple float in water without sinking to the bottom? Some things float while others sink when you put them in water, because of a concept called density.

Sometimes, understanding the theory behind buoyancy and density can be difficult and confusing for little children. In such cases, performing some simple science experiments for kids like the floating egg experiment demonstrates the concept of density to the kids.

Here is a step-by-step guide to performing the floating egg experiment:

Things You Need For The Floating Egg Experiment

• Steps To Set-Up The Floating Egg Science Experiment
• The Science Behind Floating Egg Density Experiment
• You Can Do More With Floating Egg Science Experiment

The floating egg science experiment is a simple and inexpensive way to help kids understand their lessons on density. All you need are some eggs and saltwater.

Here is a list of things you’ll need to perform the experiment:

• 2 Eggs (ensure they are the freshest eggs possible)
• 2 large glasses
• 2 – 3 cups of water 

Steps To Set Up The Floating Egg Science Experiment

Ready for an egg-citing adventure? Then, follow these instructions to perform the floating egg density experiment:

• Pour water into each of the glasses until they are about ¾ full. 
• Add the ½ cup of salt into one glass of water and stir till it is completely dissolved. 
• Add one of the eggs to the glass with plain water and see what happens. The egg will sink to the bottom.
• Now add the second egg into the glass with the salt solution. And voila! You have a floating egg.

The Science Behind The Floating Egg Density Experiment

So, why did the egg float in the salty water, while it sank to the bottom of the glass with plain water? Let’s learn about it by understanding the science behind the floating egg experiment.

• Why does the egg float in saltwater?

The egg has a lower density than the saltwater. Since the egg is lighter than the salt solution, it floats in the salty water.

Have you ever wondered why things and even humans float on the Dead Sea? It’s simple, density! The Dead Sea has an extremely high concentration of mineral salts, which increases its density. The water is so dense that even the human body is lighter than it, which makes it float.

• Why does the egg sink to the bottom of the glass with plain water?

An egg has a higher density than plain water, which is why it sinks in the glass with plain water.

• What is density and buoyancy?

Density is defined as the mass of a particular substance per unit volume. The relative lightness, or ability of a substance to float or rise on a liquid, is called buoyancy. Buoyancy is also the upward pressure or force exerted by a fluid, which causes an object immersed in the liquid to rise or move upwards. The buoyant force is directly proportional to the density of the liquid in which the object is immersed.

You Can Do More With The Floating Egg Science Experiment

It’s time to rack your little scientist’s brain. What else can you use to perform the floating egg experiment?

• Instead of salt, use sugar and see if the egg floats in that solution.
• Can the egg float in other liquids like milk, oil or even warm water?
• Try the experiment with a hard boiled egg and see if it floats in water.  

Check our kids learning section for more experiments, activities and other learning resources.

Frequently Asked Questions On The Floating Egg Experiment

What do you learn from the floating egg science experiment.

The floating egg science experiment is a great way to understand the concepts of density and buoyancy. Additionally, it teaches us that objects with lower density float, while those with higher density sink.

What do you need to perform the floating egg density experiment?

The floating egg experiment needs very few ingredients, all of which can be easily found in our kitchens. You’ll need water, salt, eggs and glasses to perform the experiment.

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Floating Eggs in Salt Water

Precaution:  Always wear safety goggles and hand gloves when dealing with chemicals. Also, take the permission from your parents for the experiment, or involve them.

Things You will Need

• Ordinary water
• Wide drinking glass
• Fill the glass with ordinary tap water.
• Place the egg in it, and watch the egg sinking to the bottom of the glass.
• Now take-out the egg from the glass and add 4 to 5 tablespoon full of salt in the water
• Stir the water in the glass to completely dissolve the salt.
• Again, place the egg back into the glass and watch the floating egg.

What is Happening?

When the egg is placed in common tap water it sinks to the bottom, because the density of water is less than the density of egg. But, when you add table salt in the tap water, its density is increased. When the density of water became higher than the density of egg, the egg floated.

Try to float an egg in the middle of the water.

To do this, follow these steps:

• Fill the glass half-way with water and add 4 tablespoons of table salt, then stir well.
• Fill a cup with ordinary tap water.
• Now, gently add the water from cup to half-filled glass so two layers of different density water don’t mix together.
• Now place the egg in the glass gently.

If two layers of water are not mixed together, the egg will float in the middle of the glass.

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Egg in Vinegar Experiment – Make a Rubber Egg

The egg in vinegar experiment is a fun way of learning about egg structure, chemical reactions, osmosis, and the scientific method . It’s a safe and non-toxic project, so it’s perfect for young investigators. Other names for the egg in vinegar experiment are the naked egg, rubber egg, or bouncy egg. The “naked” part is easy to understand, because you’re removing the shell from the egg using chemistry. The “rubber” or “bouncy” description implies the egg bounces rather than breaks. Does it work? You be the judge!

The Chemistry of the Egg in Vinegar Experiment

Vinegar contains acetic acid (CH 3 COOH), which is a weak acid . Egg shells are calcium carbonate (CaCO 3 ). Acetic acid reacts with calcium carbonate, making calcium acetate and carbon dioxide. Here is the balanced chemical equation for the reaction:

2 CH 3 COOH(aq) + CaCO 3 (s) → Ca(C 2 H 3 O 2 ) 2 (aq) + H 2 O(l) + CO 2 (g)

The calcium acetate dissolves in water, while the carbon dioxide is a gas and forms bubbles. So, the egg shell dissolves and bubbles away, leaving a naked egg.

What You Do

All you need for this project is an egg, vinegar, and a cup:

• Cup large enough for the egg
• Food coloring (optional)

Use either a raw egg or hard-boiled egg. The advantage of using a raw egg is that you can see into the inside of the egg when you are done. The advantage of using a hard-boiled egg is that it bounces after pickling in the vinegar. The raw egg bounces a bit too, but if you use too much force it breaks open and makes a mess.

• Place the egg in a cup.
• Pour vinegar over the egg until it is just covered. It’s okay if the egg floats a bit. If you like, add a few drops of food coloring. After about 15 minutes, observe the bubbles forming around the egg. The bubbles are carbon dioxide gas. They form from the chemical reaction between the acetic acid in the vinegar and the calcium carbonate of the egg shell. You may also feel that the cup is slightly warm. The reaction is exothermic, meaning it gives off heat. The bubbles and temperature change are two signs of a chemical change .
• Wait a day. Also note that the liquid becomes cloudy or scummy. This is the dissolving egg shell.
• If you remove the egg after 1 day, use a spoon. Otherwise, a raw egg easily ruptures. At this point, if you remove the egg, you can easily rinse away any remaining shell. But, you get better results if you pour off the liquid and add fresh vinegar. This is especially true if you want a rubber egg or bouncy egg. Wait another day or two, giving the vinegar time to get all the way into the egg.
• Remove the egg and rinse it off using water.

Why Rotten Eggs Float in Water

Learn the scientific reason why bad eggs float in water, while good eggs sink.

Science Experiments to Try

Now that you have a rubber egg, what do you do with it?

• Examine the internal structure of the egg. This only works if you started with a raw egg and not a hard-boiled one. Identify the egg membrane, yolk, egg white (albumin), and chalaza.
• Compare the egg without its shell to a normal egg. Notice that the egg soaked in vinegar is slightly larger than the egg with its shell. Why is this? The reason is because water entered the rubber egg via osmosis . The concentration of salts, proteins, and other molecules inside the egg is greater than the concentration in the cup. The egg membrane is semipermeable. It allows the movement of water, but not larger molecules. So, the egg swells with water to try to dilute the inside of the egg so it has the same concentration and outside of the egg. Experiment : Predict what happens if you soak the rubber egg in corn syrup, salt water, or sugar water. Compare the size of this egg with a normal egg and a rubber egg. Corn syrup, salt water, or sugar water shrink the egg because the liquid is more concentrated the interior of the egg. Here, water leaves the egg via osmosis.
• Try bouncing the egg. In addition to dissolving the egg shell, vinegar also pickles the egg. It changes the conformation of protein molecules in the egg white. Because vinegar has a low pH, it also helps preserve the egg. Experiment : Compare how well a rubber egg bounces depending on whether you started with a raw egg or hard-boiled egg.

Can You Eat the Egg?

Eating an egg after soaking it in vinegar is not a great plan. First, it won’t taste great. Second, it could make you sick. If you must eat your experiment, soak a hard-boiled egg in vinegar in the refrigerator for a few days.

Does the Egg in Vinegar Smell Like Rotten Eggs?

Mostly, the egg comes out of this project smelling like vinegar. Vinegar pickles the egg, which preserves it. But, once you remove the egg from vinegar it starts decomposing. After enough time, if you break the egg, it will stink. The odor comes from hydrogen sulfide gas, which is a product of the decomposition reactions in the egg.

Of course, if you start the project with a rotten egg, all bets are off. Rupturing the membrane releases any trapped gases. Bounce these egg with care!

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