Question

Lab partner: Molar Mass of Butane Prelab 1. Convert a pressure reading of 875 mm Hg into atm. (1 atm = 760 mmHg) 2. Look up the chemical formula for butane and calculate its molar mass? 3. A pure gas sample has a volume of 109 mL, a pressure of 723 mm Hg, and a temperature of 23.5°C. Use the ideal gas law (Eq. 1) to calculate how many moles of gas are present in this sample? (Be sure you have the proper units for each variable prior to plugging the values into the equation.) 1. A sample of butane is collected over water as shown in Figure 1. The total gas pressure inside the collection device is 745.2 mm Hg at a temperature of 25°C. What is the partial pressure (in atm) of butane under these conditions? (Refer to the Introduction) 5. One hot afternoon, you go through a drive-thru for a soda. You get to take about 3 drinks of soda prior to running an errand that takes 45 minutes. After the errand, you return to your vehicle excited for a swig of that fabulous soda and find it's not the same soda you started out with. Ignoring the fact of the ice melting, explain what happened to change the quality of your soda. Which gas law explains this (you may have to dig a little deeper into your textbook for this law)? 119-

Answer 1

= 1.15 atm 1 875 mmHg x lahm 760mming 2. Butane Ca Ho Molar mass = 4x12.0107 + 10x1.0078 = 58.12 g/mol.