This Lab Key is meant to stimulate your thinking and planning. It DOES NOT provide a complete set of procedures and calculations. Several hydrocarbons are gases at normal room conditions. Any of these can be liquefied by placing them under pressure, as in a disposable "butane" lighter. When the valve of the lighter is opened, the drop in pressure causes the liquid to be released as a gas. Hydrocarbons are insoluble in water, so they can be bubbled through water with very little of it going into solution. This makes, water displacement is a good method for collecting them. The current atmospheric pressure in the CHS chemistry lab is available here.   Consider the following: The fuel inside a "butane" lighter can be collected as a "wet" gas. The mass of the lighter will change as gas is removed. The mass of the gas collected can be determined. The number of moles (n) of gas collected can be determined. The molar mass (M in g/mole) of the gas collected can be determined. HINT: In the first draft, the procedures for many lab groups produce a significant "measurable error" in the mass of the collected gas.   Do yours?