4E: A cake recipe calls for 2 eggs and 4 cups of flour, but you have 3 eggs, and 3 cups of flour. In this example, flour is our limiting reagent, that is, its small amount preventing you from completing the reaction of making the cake since we do not have enough (while we have more than enough eggs to make the cake). We’ll extend this simple example to chemical reactions with atoms and molecules. You'll learn to balance chemical reactions, a concept that will be applied to several other problems in chemistry.
In this video David explains what specific gravity means. He also shows how to calculate the value for specific gravity and use it to determine the percent of an object that will be submerged while floating.