what\'s wrong with my answer? Enter your answer In the provided box You analyze
ID: 887440 • Letter: W
Question
what's wrong with my answer? Enter your answer In the provided box You analyze a sample of volatile liquid propyl acetate (C5H10O2) by placing a small volume of it In a round-bottomed flask with a volume of 538.0 mL and an evacuated mass of 132.478 g. You submerge the flask in a water bath at 100.0 C and allow the volatile liquid to vaporize. You then cap the flask and remove It from the water bath. What will the mass of the 538.0-mL flask be after evaporation of the propyl acetate? (Assume the pressure in the laboratory s 1.000 atm.)Explanation / Answer
We will have to find the mass of the condensed vapour in the flask, but before that we will calculate the number of moles of condensed vapour in the capped flask,which is equal to the mass of the vapour that occupies the flask at elevated temperature and atmospheric pressure.
n=PV/RT
P=atmospheric pressure( as the opening of the flask is small and allows the vapour to escape at controlled rate so that vapour pressure of liquid equals atm pressure)=1 atm
V=volume of flask
T=temp of water bath and the boiling liquid=100oC=373K
R=gas const=0.0821L atm/K mol
n=1atm * 538 ml *10^-3 L/ml/0.0821 L atm /K mol * 373K=0.0175 moles of vapours
Now molar mass of propyl acetate=102 g/mol
so 0.0175 moles of it=102g/mol*0.0175 moles=1.785 g
mass of flask=mass of condensed vapour + evacuated mass of the flask=1.785 g+132.478=134.263 g
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