MOLAR MASS OF BUTANE

Molar Mass of Butane

Molar Mass of Butane

Introduction

Hydrogen gas (H2) is colorless, odorless and the most abundant element in the universe. Hydrogen combines with oxygen to make water which is essential to life. Combined with carbon, it makes up a large class of organic compounds called hydrocarbons (Roman, 2009). Hydrocarbons include the gas you use for your car to the propane you use to light your barbecues. Hydrogen gas is also used to produce ammonia, which is used for fertilizer production. Hydrogen is also a very flammable and explosive gas. Hydrogen gas, when mixed with oxygen gas, will explode upon ignition and burn violently. Great care must be taken when working with hydrogen gas. In the laboratory, hydrogen gas can be generated by reacting acids with metals such as magnesium. The magnesium oxidizes to the magnesium ion and the hydrogen is reduced to the diatomic gas. The known reaction being performed in today's experiment is:

In this experiment, HCl is present in excess, so each mole of magnesium you start with should lead to one mole of H2 gas. The reaction i will be working with in the second part of this experiment is:

The M represents an unknown metal. Again, HCl is in excess so each mole of hydrogen produced came from one mole of unknown metal. The unknown metal will be identified by determining its molar mass. In Part I of this experiment, you will test this stoichiometric relationship from equation (1) with a known amount of magnesium. In Part II, you will use this relationship from equation (2) to determine the molar mass of the unknown metal you are given. In order to calculate this molar mass for Part II, you will first have to determine how many moles of hydrogen gas are produced in the reaction. We are going to assume ideality and use the following equation:

The value of the constant R is 82.05 mL atm/mole K and Vb, is the volume change in the buret. Patm is the atmospheric pressure and PH2O is the vapor pressure of water at a certain temperature (Ramsey, 1989). The temperature used in the equation is the temperature measured after the reaction has occurred since the reaction between metals and acids is exothermic. A table of these vapor pressures at different temperatures is at the end of this laboratory experiment. Be sure to estimate between temperatures when necessary. Remember, ...