Question

# A student observes that a 126 mL dry flask with a foil cup weighs 50.162 g....

A student observes that a 126 mL dry flask with a foil cup weighs 50.162 g. The student then adds 5 mL of an unknown volatile liquid and heats flask in a boiling water bath at 99.2 C Until all liquid disappears. The flask, foil, and unknown after heating that is dry and cool weigh 50.610 g. The barometric pressure in the laboratory is 743.3 mmHg; the laboratory temperature averages 22.3 C; the vapor pressure of the unknown liquid is 160 mmHg at 20 C and the density of dry air at STP is 1.2929 g/L.

a. what are the experimental conditions of T and P that will be used to Calculate the mass of air in the flask?

b. Calculate the density of air at the experimental conditions identified in part A.

c. Calculate the mass of air in the flask before the liquid was added.

d. Calculate the partial pressure of air in the flask after the liquid was heated and then cooled.

e. Calculate the mass of air in the flask after the liquid was heated and then cooled.

f. Calculate the mass of air lost.

g. Calculate the mass of liquid, vapor, and air in the flask before you correct for air lost.

h. Calculate the mass of liquid, vapor, and air in the flask after you correct for air lost.

i. Calculate the molar mass of the unknown liquid.

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