Molar mass of a gas

background [prelab assignment (10 points) due at the beginning of the lab]

design an experiment to determine the molar mass of a gas

sketch a data table for this lab containing entries for all required experimental measurements (i.e. reveiw purpose & content of lab report)

purpose

determine the molar mass of a gas

~~using a 50 versus 125 mL flask~~

~~does the size of a flask affect the accuracy of determining the molar mass of a gas ?~~

materials

balance, flask (

~~50 or~~125 mL), aluminum foil, ice, graduated cylinderBunsen burner, beaker, water, pressure & temperature probe; metal ring, ring stand

~ 1 mL hexane or cyclohexane

~~for both flasks~~

methods / data analysis

student design [hint: see textbook problem 10.37]

other comments

water bath temperature < 90 °C; do not boil

wipe underside of aluminum foil after water bath incubation / prior to measuring its mass

Content of lab report [ 20 points]

data analysis (10 points)

data table of your experimental measurements

determination of the molar mass of the gas - based on your group's data (show your work)

~~statistical analysis of class data (see purpose; include interpretation of p-value)~~error analysis [10 points]

calculate % error

describe 2 pausible / nontrivial experimental errors & rationalize its effect on your determination of the molar mass of a gas

**resources**:

lab activity source (examples): site 1 [access 4 / 2009]