Salt egg water experiment
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Answered by
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Key concepts
Density
Mass
Volume
Concentration
Buoyancy
Water
Introduction
Have you ever wondered why some objects float in water and others sink? It has to do with the density of the objects compared with the density of the water surrounding them. If an object is less dense than the water around it, it will float. Because salt water is denser than freshwater, some things float more easily in the ocean—or extremely salty bodies of the water, such as the Dead Sea. You can make your own dense water by adding salt to tap water. In fact, if you add enough salt, you can make the water so dense that an egg will actually float in it! Explore how this works in this science activity.
Background
If you put an egg in a cup of tap water, it will sink to the bottom. Why is this? Because the density of the egg is higher than the density of tap water, so it sinks. Density is the mass of a material per unit volume. For example, the density of freshwater under standard conditions is approximately one gram per cubic centimeter.
But, if you add enough salt to the water, the egg will actually float back up to the surface! Adding salt to the water increases the density of the solution because the salt increases the mass without changing the volume very much.
When enough salt is added to the water, the saltwater solution's density becomes higher than the egg's, so the egg will then float! The ability of something, like the egg, to float in water or some other liquid is known as buoyancy. But just how much salt is needed to make an egg float? In this science activity you'll figure that out by making solutions with varying concentrations of salt in them.
Materials
One egg
Water
Measuring cup
Large container, such as a large bowl or cooking pot (It must be able to hold at least three cups.)
One half cup of table salt
Five cups that hold at least 16 ounces each
Permanent marker (if you are using plastic cups) or masking tape and a pen (to label nondisposable cups)
Three spoons for mixing salty solutions
Soup spoon for egg transfers
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Preparation
Take the egg out of the refrigerator and allow it to warm to room temperature. Be sure to always wash your hands after handling uncooked eggs because they may carry salmonella.
Pour one and one half cups of water into your large container.
Add one half cup of salt to the large container and stir to dissolve some of the salt (it will not all dissolve yet).
Add one more cup of water to the large container (making two and one half cups total) and stir to dissolve the remaining salt. The salt should be completely dissolved before you go on to the next step. It may take several (five to 10) minutes of stirring, so you may need to be patient. Why do you think it's important to start out with a solution that has such a high concentration of salt?
Arrange the five cups on a surface, going in a line from left to right. Label the cups 1 to 5. If you are using plastic cups, you can use a permanent marker to label them. If you are using nondisposable cups, you can use masking tape and a pen to label them.
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Procedure
Add three quarters cup of the salty solution you prepared to cup 1.
Add three quarters cup of plain tap water to cups 2 through 5. (Cup 5 will be plain tap water.)
Add three quarters cup of the salty solution you prepared to cup 2 and mix it. What is the salt concentration in cup two compared with cup one?
Add three quarters cup of the salt solution from cup 2 to cup 3 and mix it. What is the salt concentration in cup 3 compared with cups 1 and 2?
Add three quarters cup of the salt solution from cup 3 to cup 4 and mix it. What is the salt concentration in cup 4 compared with the other cups?
Use a soup spoon to place an egg in cup 5. Does the egg float?
Use the spoon to take the egg out and place it in cup 4. Does the egg float?
Repeat this process with cups 3, 2 and then 1. In which cup does the egg first float? If the egg floated in more than one cup, did you notice any difference in how it floated? What does this tell you about the density of the egg?
Hope this help you
Density
Mass
Volume
Concentration
Buoyancy
Water
Introduction
Have you ever wondered why some objects float in water and others sink? It has to do with the density of the objects compared with the density of the water surrounding them. If an object is less dense than the water around it, it will float. Because salt water is denser than freshwater, some things float more easily in the ocean—or extremely salty bodies of the water, such as the Dead Sea. You can make your own dense water by adding salt to tap water. In fact, if you add enough salt, you can make the water so dense that an egg will actually float in it! Explore how this works in this science activity.
Background
If you put an egg in a cup of tap water, it will sink to the bottom. Why is this? Because the density of the egg is higher than the density of tap water, so it sinks. Density is the mass of a material per unit volume. For example, the density of freshwater under standard conditions is approximately one gram per cubic centimeter.
But, if you add enough salt to the water, the egg will actually float back up to the surface! Adding salt to the water increases the density of the solution because the salt increases the mass without changing the volume very much.
When enough salt is added to the water, the saltwater solution's density becomes higher than the egg's, so the egg will then float! The ability of something, like the egg, to float in water or some other liquid is known as buoyancy. But just how much salt is needed to make an egg float? In this science activity you'll figure that out by making solutions with varying concentrations of salt in them.
Materials
One egg
Water
Measuring cup
Large container, such as a large bowl or cooking pot (It must be able to hold at least three cups.)
One half cup of table salt
Five cups that hold at least 16 ounces each
Permanent marker (if you are using plastic cups) or masking tape and a pen (to label nondisposable cups)
Three spoons for mixing salty solutions
Soup spoon for egg transfers
FEATURED PRODUCT

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Preparation
Take the egg out of the refrigerator and allow it to warm to room temperature. Be sure to always wash your hands after handling uncooked eggs because they may carry salmonella.
Pour one and one half cups of water into your large container.
Add one half cup of salt to the large container and stir to dissolve some of the salt (it will not all dissolve yet).
Add one more cup of water to the large container (making two and one half cups total) and stir to dissolve the remaining salt. The salt should be completely dissolved before you go on to the next step. It may take several (five to 10) minutes of stirring, so you may need to be patient. Why do you think it's important to start out with a solution that has such a high concentration of salt?
Arrange the five cups on a surface, going in a line from left to right. Label the cups 1 to 5. If you are using plastic cups, you can use a permanent marker to label them. If you are using nondisposable cups, you can use masking tape and a pen to label them.
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Procedure
Add three quarters cup of the salty solution you prepared to cup 1.
Add three quarters cup of plain tap water to cups 2 through 5. (Cup 5 will be plain tap water.)
Add three quarters cup of the salty solution you prepared to cup 2 and mix it. What is the salt concentration in cup two compared with cup one?
Add three quarters cup of the salt solution from cup 2 to cup 3 and mix it. What is the salt concentration in cup 3 compared with cups 1 and 2?
Add three quarters cup of the salt solution from cup 3 to cup 4 and mix it. What is the salt concentration in cup 4 compared with the other cups?
Use a soup spoon to place an egg in cup 5. Does the egg float?
Use the spoon to take the egg out and place it in cup 4. Does the egg float?
Repeat this process with cups 3, 2 and then 1. In which cup does the egg first float? If the egg floated in more than one cup, did you notice any difference in how it floated? What does this tell you about the density of the egg?
Hope this help you
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