Quique Garcia
Date of Lab:3/21/14
Introduction The purpose of the lab was to find the molar mass of butane threw an experiment. [1] Butane is a flammable gas found commonly in lighters as an energy source. [2] Molar mass is how much a compound weighs, based on what elements are found in it, and how much of the element is present. If the volume of butane is found then the molar mass becomes possible to find as well. Dimensional analysis will be used in order to convert the volume of the gas collected to mass.
Volume/24.5 = Number of Moles
Grams per Mole (Molar Mass) = grams of butane/ moles of butane Results/Data
The lab was completed as follows. The equipment need was gathered. A pneumatic trough, a graduated cylinder, a lighter, a scale, and water where used. The mass of the lighter was found on the scale before beginning. This was followed by the pneumatic trough being filled to roughly about 3/4th of the way full. The graduated cylinder was then filled completely. Someone’s hands where used to cover the top of the graduated cylinder in order to prevent any water from escaping. The graduated cylinder was flipped upside down in and submerged in the water. If was made sure that no air bubbles entered the graduated cylinder. While having the cylinder held slightly at an angle the lighter was placed underwater and under the cylinder, and the butane gas was released into the graduated cylinder. The gas was collected until reaching 75mL. The lighter and graduated cylinder where removed from the water and the lighter was dried. The water was discarded and the mass of dry lighter was found.
Procedure:
Molar Mass of Butane
1) Obtain a butane lighter
2) Find the mass of the butane lighter using a scale and record (Data table at end) 3) Fill a pneumatic trough and 100 mL graduated cylinder with water
4) Cover with hands and flip upside down in the trough without letting any water out or air in
5) Place the lighter underneath the graduated cylinder and release the butane into the cylinder 6) Continue releasing butane until the gas lowers the water to 75mL 7) Dry the lighter, find the new mass of the lighter and record (Data table at end)
8) Add one of the compounds to each pile of sodium acrylate 9) Record on Data Table (Table on last page) Observations:
The mass of the butane collected was very light.
The water and room where not at STP, therefore volume conversion would have to change.
Depending on how the lighter was tipped more or less butane could flow out of the lighter at once.
Questions
1. If an air bubble had been in the flask before it filled with butane then the air bubble would have contributed to reaching 75 mL, which was supposed to only be 75mL of butane, thus making the measurement less precise.
2. The standard molar volume (22.4L/mol) could not be used in the investigation due to the fact that the standard molar volume only applies if the conditions were in STP. The water was not at STP.
Discussion
The purpose of the lab was to find the molar mass of butane C4H10 . This was done through the use of dimensional analysis, mole conversions of volume to moles, and also from moles to mass.
The molar mass of butane C4H10, as proven by the data obtained during the lab was able to be found.