Objective: To understand how density works and how you can change the density of a liquid.
Procedure: 1) Fill 3 glasses with 250ml of water and place a fresh egg in one of the glasses, watch as it sinks.
2) Put 4 tsp. of salt into one of the glasses stir it up and place an egg in the water. Watch as it floats.
3) Put 4 tsp. of salt into the final glass stir it up and pour out some of the salt water. Now place an egg in the water. Slowly and carefully pour fresh water into the glass of salt water and watch as the egg sinks down till the middle.
Density is the amount of space something takes up per volume and when you add more mass to the same amount of space being taken up you can change the density of a liquid. When you drop a raw egg into fresh water the egg doesn’t displace enough water making the egg denser then the water around it. Creating an unbalanced force which sends the egg to the bottom of its container. When you add 4 tsp. of salt to 250 ml of water and stir, the salt crystals break down into molecules and fill in the holes in-between the water molecules. The solution now has more mass in the same space or volume, which changes the density of the water.
When you add the egg to the salt water you displace the same amount of water but that space has more molecules in it and the egg becomes less dense then the salt water around it. When you slowly add fresh water to salt water the less dense fresh water floats on top of the more dense salt water and you create a density column of water. The egg sinks through the less dense fresh water and floats on the more dense salt water. To make anything that doesn’t float, such as a bowling ball that doesn’t float, you just have to increase or lower the density of the liquid you want the object to float in.