Abstract: In this experiment we combined a strip of magnesium with hydrochloric acid in a buret and measured the amount of hydrogen gas the reaction produced. We also tracked the pressure inside a syringe as the volume of the syringe increased and decreased.
Introduction: The moles and density of the hydrogen gas that is produced in this experiment can be calculated using the combined gas law equation and some simple measurements. Volume, density, and temperature were recorded throughout the experiment. The density of hydrogen gas is known at STP so the units recorded in the experiment can be converted and then the results can be compared to the known density. When temperature is kept constant, the volume of a gas is inversely proportional to the pressure. This idea is known as Boyle’s Law, and was discovered by Robert Boyle in 1662 (lab handout) I predict that as we decrease the volume in the syringe, the pressure will increase.
Methods: The temperature and pressure of the room was recorded and remained constant throughout each experiment while a small magnesium strip (.037 g) was weighed and attached to a wire, which was attached to a rubber stopper. A large beaker was filled with water and then the temperature of the water was recorded. A ring stand to hold the buret was set up, with the water beaker placed underneath. 10 mL of HCl was added to the empty buret and the rest was filled with distilled water. The stopper, complete with wire and magnesium strip, was placed on the top of the buret, and then the buret was inverted into the water beaker and secured in place on the stand. The stopper was quickly removed from the buret, leaving the magnesium to react with the HCl inside. The magnesium slowly disappeared in a bubbly reaction and the gas inside the buret was visibly increasing. To record the data for the Boyle’s Law lab, we connected the syringe to a small computer that was able to display the pressure that was inside the syringe at any given volume. Any extra volume inside the syringe was compensated for and the pressure was recorded at the following volumes: 20.8 mL, 18.4 mL, 15.8 mL, 13.4 mL, 10.8 mL, and 5.8 mL.
Results: The Ideal Gas Law can be used to determine the…