Question

A student was given a 10 mL sample of a clear, colorless liquid. She was assigned the task of identifying the unknown liquid and was told that the sample could be methanol (CH_3OH), acetone (C_3H_6O), or ethanol (C_2H_5OH). She decided to attempt to determine the molar mass of the liquid by the vapor density method, which involves completely vaporizing a small sample of the liquid, cooling it and determining the mass of the condensed vapor. She also collects the volume of the container, temperature and pressure when the liquid is vaporized. The following data were collected: Fill in the missing data in the data table. What could account for the difference in the masses in the two trials? Determine the molar masses for each trial, showing all calculations. The student reported that the unknown liquid was definitely methanol. Do you agree with her conclusion? Why or why not? The formulas used in the calculations assume that the gas behaves ideally. State one factor that could cause the vapor to deviate from ideal behavior. State whether the factor would cause the experimental molar mass to be too high, too low, or remain the same.

Answer 1

Mays the o. 276 O.318 g water bah 372.9s K 372.75 K Atmosphexie press 0.98 tm.S tm harec c) m = 0,276 9乂 .0821 乂312.9 S 29.61 jlml TRIAL-2 -