The hypothesis of floating egg in salt water is that salt water and fresh water have different densities. Since an egg will sink within regular water, adding salt to the water will increase the density of the water and allow the egg to float. An egg floats in salt water because salt water is more dense than water straight from the tap. The greater buoyancy allows the egg to float in the salt water, provided it is salty enough. In order for something to float, the buoyant force has to greater than or equal to the weight of the object. The buoyant force is equal to the weight of the liquid that is displaced by the object. To figure out the weight of the water that is displaced, you multiply the density of the water by the volume and then multiply that by gravity. The density of fresh water is less than salt water; therefore the weight of the water displaced will be greater in the case of the salt water, resulting in a greater buoyant force. The more salt that is present in the water the more buoyant an object becomes. Salt water has more particles with which to hold up the egg. This is because rather than floating and taking up space, the salt dissolves into ions which are attracted to the water molecules and bind very tightly to them, packing more matter into the space. The mass of the ordinary water consists of the mass of the hydrogen and oxygen that it contains. Salt water has the additional mass of the sodium and chlorine atoms that dissolve into the water. To test this in an experiment, fill up two glasses with fresh water. Add six tablespoons to one of the glasses and place an egg in each cup.
