Why egg floats in salt water

What do you think will happen if you put a boiled egg in fresh water? What do you think will happen if you put a boiled egg in salt water?

What do you think will happen if you pour the fresh water into the salt water and put an egg into the mixture? I will now let the children experiment with the materials on their desk to see if their predictions are correct. They will place one egg into each cup and observe what happens.

This step must be done very carefully or it will not work. It is very important that the fresh water and salt water do not mix. Now, they must place an egg into the cup that holds the salt water and fresh water and observe what happens. We will have a whole group discussion about the observations made by the students. The students will lead this discussion. I will simply be there to guide them in the right direction.

Assessment of the students will occur in several ways. While the students are speaking about their observations, I will listen to the discussion going on between them and their group members. This will help me see if the students are understanding the basic concepts. I will only be able to assess a few of the students during the creative drama.

I will try to select the students that I did not hear while they were experimenting. During colloquium, I will also have a chance to listen to the whole group discuss the difference between salt water and fresh water. Predict- The students will make predictions about what will happen to the egg in the different types of water. This is a wonderful website that I used while preparing for this lesson.

It has many great ideas and experiments, all dealing with the ocean. It also has a list of questions your students should be able to answer after completing the experiment. 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. Observations and results Did the egg float in cup 1 and 2, but not in cups 3, 4 or 5?

You likely saw that the egg floated best in cup 1, floated a little less in cup 2 but part of it was above the surface and did not float in the other cups. Cup 1 had the undiluted salty solution that you originally prepared, which was one half cup of salt in two and one half cups water total. The concentrations of the salt solutions in cups 2 to 4 were halved as you increased in cup number; for example, the concentration of the salt in cup 2 was half that of cup 1, and the concentration of the salt in cup 3 was half again of cup 2.

Cup 5 had plain tap water. The egg should have sunk in cups 3, 4 and 5 because the density of the egg was higher than the density of the solutions or plain tap water in those cups. Cups 1 and 2 had more salt in them than the other cups with cup 1 having the most salt , which means these solutions were denser. The egg should have floated with part of it above the water surface in these two cups because the solutions were denser than the egg.

What happens to the egg? Did you know there is a way to make it float? Continue on in the experiment to find out how. Step 3 — Add 3 Tablespoons of salt to the water and stir until it is completely combined. What do you think will happen if you place the egg into the glass with the salt water? Write down your hypothesis prediction and then test it to see if you were right. Step 5 — Next carefully place the second egg into the glass with the salt water.

Take a moment to make some observations. Why do you think one egg sinks and the other egg floats? Next, carefully pour more fresh water until the glass is nearly full be careful to not disturb or mix the salty water with the plain water. The egg is denser than the fresh water more molecules per square inch , this causes it to sink. When you start dissolving salt in the water, this is increasing the density adding more molecules per square inch. Eventually the water becomes denser than the egg causing the egg to float.