The Molecular Weight of Butane Gas “Pevnert” Power

Experimental Design A butane lighter will be massed and then submerged in water under the lip of a eudiometer (gas collection device). Butane gas will be released into the eudiometer until the collected volume approaches 49 – 49.5 ml. The collected gas will be transferred to a water bath and then allowed to rest until the temperature of the gas is the same as the water bath. The butane lighter will be repeatedly warmed with a hair drier and then massed until the mass becomes stable (all water removed). The volume of the butane will be read when the water level inside the tube is the same as the water level outside of the tube. Under those conditions the pressure inside of the tube is the same as the prevailing atmospheric pressure. Dalton’s law will be applied to find the pressure of the dry gas and a temperature conversion from Celsius to Kelvin will be done. Finally, using the standard graphic organizer for assessing gaseous systems the data will be displayed and processed to find the experimental molecular weight of butane.

The Initial Mass of the Butane Gas With the wind barrier down the mass of the butane lighter stabilized at 13.925 g.

Technique for Collection After filling the eudiometer with water the instrument was inverted over the butane lighter. To prevent loss of the gas steps were taken to secure the tube by pressing it to the side of the beaker . We were careful to place the eudiometer over the exposed nozzle of the lighter.

Pretty Bubbles The released butane gas rose to the top of the gas collection tube. After 49 ml of gas was collected the system was transferred to a water bath.

Transfer Technique During the transfer we were careful to not let air enter into the tube. This is a job for large fingers.

Measuring the Volume and Temperature The volume was measured when the water level inside and outside of the tube was the same. With this technique the pressure inside was the same as the prevailing atmospheric pressure.

Drying the Lighter The outside of the lighter was dried with a towel. Then we directed a warm hair drier to the top to remove any trapped water. We massed the lighter and repeated the procedure until the mass stabilized.

Final Massing After the mass stabilized we recorded the data in the standard gas system graphic organizer and then proceeded with an analysis.

Data:

Data Processing:

Final Remarks This was a great way to finish the unit on gas laws. To be successful we had to employ many of the skills we acquired throughout the unit. We approached the study in teams. Each team was given board space for group discussion. The best teams allocated the key jobs so that everyone had a task. There were no spectators. At the board the team gathered and publically processed the data. At the end of the project a single report was submitted. This is collaborative effort at the highest level.