A sample of a volatile liquid is vaporized completely in a 240 cm3 flask at 135°C and 1200 mm Hg. The condensed vapor (liquid) weighs 0.837 grams. What is the molecular weight? The liquid contains 64.9% carbon, 13.5% hydrogen, and 21.7% oxygen. What is the molecular formula?
2007-07-01 03:57:10 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Calculate number of moles with formula pV=nRT
n= pV/RT
p= 133.2*1200 Pa V= 240*10^-6 m^3
R =8.31 J/K T= 135+273=408= 0.01132mole
this corresponds to 0.837g
so molecular weight is 0.837/0.01132=74g
mass of carbon 74*0.649=48g so C4
mass of hydrogen=74*0.135=10 so H10
mass of oxygen 0.217*74 =16 so O
formula C4H10O (alcool butyric)
2007-07-01 04:42:24 · answer #1 · answered by maussy 7 · 0⤊ 0⤋
use pv = nrt to discover moles of the liquid. confirm rigidity is in atm volume is liters r = 0.0821 and T is kelvin. Then use grams/moles to get the molar mass. as quickly as you have the molar mass use the probabilities to make your suggestions up what proportion grams of each atom you have... then convert to make your suggestions up what proportion moles of each atom you have. those values could be the subscripts interior the molecular formulation
2017-01-23 07:29:46 · answer #2 · answered by rammurti 3 · 0⤊ 0⤋