Welcome to "A Submarine Adventure" the first "wet lab" in this manual (No pun intended). A "wet lab" in chemistry is simply a lab involving the use of chemicals and although this lab will only expose you to water, you should realize that water is indeed a chemical and a very important one at that. The purpose of this lab however, is not to focus on water, but rather to use water to illustrate a very basic physical concept, density.  Density is calculated as the mass of an object divided by its volume (d = m/V). Density is an intensive property, meaning that it is a property that is the same no matter how much of a substance is present. Density is an important property to understand because it allows us to determine whether objects will float or sink when placed in a liquid or even a gas. Generally, substances float if their density is less than the density of the medium they are placed in. This is why small rocks sink to the bottom of a pond, while wooden objects, even large logs, float.
As scientists have discovered more about the concept of density, we (the science community) have learned to harness this knowledge for our own use. One of the most readily recognized uses of the concept of density is the modern invention: the submarine. Since steel is certainly much denser than water (7.83 g/cm3 versus 1.00 g/cm3), one could ask the question, “How does a submarine that contains several tons of steel float in the ocean?” The answer is that a submarine takes advantage of the air space found within it. If the ship's total volume is much greater than its mass, then its density is less than that of the water around it and it will remain afloat. In order to raise and lower the submarine in the ocean, the captain of the sub opens the hull to allow water in and in doing so increases the submarine’s mass; this causes the sub’s density to increase and the submarine to submerge. In order to raise the submarine to the surface, the water is released (or pumped out), reducing the submarine’s density. The mechanical system that performs the influx and outflow of water into a submarine is a called a ballast system.
The purpose of this lab is to investigate the concept of density by determining the identity of some metal objects based on their experimentally determined densities and by building your own ‘mock’ submarine. In doing so, you will learn some other very basic techniques that you will use again and again in the weeks to come. These techniques are the use of the analytical balance to weigh objects and the measurement of a liquid in a graduated cylinder.
Since a majority of the chemistry you will be completing in the lab is aqueous in nature, you will be measuring the volume of liquids in almost every lab. As with any process in science there is a correct way to make the measurement. Please pay close attention to your instructor's demonstration of the proper way to fill and read your graduated cylinder. The other technique you will learn in this lab is the proper way to weigh an object. The analytical balance is a vital tool you will use to measure everything from solid reagents used to make solutions to products of a chemical reaction. An accurate weight is vital to both the production of accurate data and to the successful interpretation of an experiment. Your instructor will demonstrate the proper use of the analytical balances.