A student was assigned the task of determining the identity of an unknown liquid
ID: 479405 • Letter: A
Question
A student was assigned the task of determining the identity of an unknown liquid. The student weighed a dean, dry 250-mL Erlenmeyer flask. The student completely filled the flask with water. He then proceeded to weigh the flask containing the water. mass of 250-mL Erlenmeyer flask 78-639 g mass of 250-mL Erlenmeyer flask and water 327.039 g Assuming the density of water is 1.00 g/mL at ambient temperature, what is the exact volume (in mL) of the 250-mL Erlenmeyer flask? Next the student added 5.2 mL of an unknown liquid to the dry 250-mL Erlenmeyer flask (same flask used in Question 1). He placed the flask in a boiling water bath and left it there until the liquid completely vaporized. The student measured the temperature of the boiling water bath to determine the temperature of the gas inside the flask. The temperature of the water bath was 99.3 degree C Atmospheric pressure was 751 torr when the liquid completely vaporized. What is the temperature of the gas in Kelvins? What is the pressure of the gas in atmospheres?Explanation / Answer
Mass of water = Mass of Flask + Water - Mass of Flask = 327.039 - 78.639 = 248.4 gms
density = 1gm/ml
1 = 248.4 / V
V = 248.4 ml
The temperature of gas in Kelvin is = 99.3 C + 273.15 = 372.45 K
1 atm = 760 torr
751 torr = 751/760 = 0.988 atm
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