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Lab 8 - Determination of the Molar mass of Volatile Liquid

Lab 8 - Determination of the Molar mass of Volatile Liquid...

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Arjun Rastogi 4 th Hour 2/15 /08 Determination of the Molar Mass of Volatile Liquid I Purpose: The purpose of this lab is to calculate the molar masses of several volatile liquids based on measurements of their vapor density. II Procedure: Place a 400-mL beaker on hot plate and fill the beaker with 300-mL of water, along with boiling stones. Turn on hot plate. Obtain 3 15-mL jumbo Beral-type pipets and pull the thin stems so each has a very fine tip. Cut the pipet so its tip is less than 1-cm long and label each pipet as #1, #2, and #3. Mass each pipet and record in data table. Obtain 1-2 mL of ethyl alcohol into each pipet and secure the tubing with a tes t tube clamp/ Lower the pipets into the boiling water bath, making sure that each bulb is below the water line for at least 5 min. Record the temperature of the boiling water and barometric pressure of the room in Data Table 1. Remove the pipets when all liquid has evaporated inside the pipets and cool them by lowering the pipets into a water bath of room temperature in a 400-mL beaker. Dry the pipets and mass each recording results in Data Table 2. After massing each pipet empty them and fill with deionized water to rinse them out. Repeat this entire procedure for acetone and isopropyl alcohol. II I Data Collection: Temperature of boiling water bath 99.0 °C + 273 K = 372K Barometric pressure 738 mmHg x 1 atm = 0.971 atm 760 mmHg Temperature of room temp. water bath 24.0 °C + 273 K = 297 K Density of water at room temperature .9973 g/mL Data Table 1 Jumbo Pipets Jumbo Pipet #1 Jumbo Pipet #2 Jumbo Pipet #3 Mass of empty pipet 1.578 g 1.803 g 1.756 g Mass of pipet and water 16.191 g 16.374 g 16.356 g Mass of water in filled pipet 14.613 g 14.571 g 14.600 g Volume of pipet 14.65 mL 14.61 mL 14.64 mL Data Table 2 Volatile Liquids

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Trail 1 Trail 2 Trail 3 Ethyl Alcohol Mass of pipet and condensed ethyl alcohol 1.602 g 1.830 g 1.783 g Mass of condensed ethyl alcohol 0.024 g 0.027 0.027 g Molar mass of ethyl alcohol 51 g/mol 58 g/mol 58 g/mol Acetone Mass of pipet and condensed acetone 1.605 g 1.832 g 1.786 g Mass of condensed acetone 0.027 g 0.029 g 0.030 g Molar mass of acetone 58 g/mol 62 g/mol 64 g/mol Isopropyl Alcohol Mass of pipet and condensed isopropyl alcohol 1.608 g 1.839 g 1.788 g Mass of condensed isopropyl alcohol 0.030 g 0.036 g 0.032 g Molar mass of isopropyl alcohol 64 g/mol 77 g/mol 69 g/mol IV Data Analysis: Pre-Lab Questions: 1) A determination of the molar mass of methyl alcohol (CH 3 OH) yielded the following data: Temperature of boiling water bath 99.5 °C + 273 K = 373 K Barometric pressure 738 mmHg x 1 atm = 0.971 atm 760 mmHg Temperature of room temp. water bath 24.0 °C + 273 K = 297 K Density of water at room temperature .9973 g/mL
Trail 1 Mass of empty pipet 1.557 g Mass of pipet and condensed methyl alcohol 1.571 g Mass of pipet and water 16.001 g Mass of condensed methyl alcohol 1.571 g - 1.557 g = 0.014 g

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