Report all results to the correct number of significant figures. An empty flask

Question

Report all results to the correct number of significant figures. An empty flask weighs 127.038 g. After vaporization of a sample of volatile liquid as described in the experimental write-up, at a measured temperature of 99.8 degree C, the flask is sealed, cooled to room temperature, and weighed. The mass is now 127.405 g. The measured P_atm is 759.1 torr. The flask is rinsed and filled completely with water at 21.8 degree C. The mass of the flask is now 376.136 g. Calculate the volume of the flask from the mass of water contained in the flask and the density. Calculate the molar mass of the volatile liquid.

Explanation / Answer

Q1.

m = 127.038 g of flask

mass + volatile = 127.0405

mass of volatile = 127.405-127.038 = 0.367 g of volatile

m water = 376.136-127.0405 = 249.0955 g

D = 0.9982071 g/mL

V = mass/D = 249.0955/0.9982071 = 249.542 mL

then, the volume of flask = 249.542 mL

Q2.

find MM = mas s/ mol

we need moles

PV = nRT

n = PV/(Rt) = 759.1*0.249542/(62.3*(99.+273.15))

n = 0.0081702

MM = 0.367 /0.0081702 = 44.91 g/mol

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