calculate: the volume of the erlenmeyer flask, volume of vapour at STP, mass of
ID: 552305 • Letter: C
Question
calculate: the volume of the erlenmeyer flask, volume of vapour at STP, mass of vapour, molar mass of unknown.
pressure is 17.5 mmHg.
Table 1: Data to determine molar mass of the unknown liquid Unknown number Barometric Pressure Temperature of boiling water bath Mass of flask, cap and condensed liquid Mass of flask and cap 92.5 C Table 2: Data to determine volume of the Erlenmeyer flask used in your experiment Temperature of water used to determine volume of the flask .9 Density of water at the temperature stated on the previousrow Mass of flask, cap and water Mass of flask and ca
Explanation / Answer
mass of the water = 243.260-101.0450 = 142.215 gm
density of water at 20oC= 0.9982 gm/mL
mass of water / volume of the flask = 0.9982 gm/mL
142.215 gm / 0.9982 gm/mL = 142.47 mL = volume of the erlenmeyer flask = V1
P1 = 17.5 / 760 = 0.02302 atm ; V1 = 142.47/1000 = 0.14247 L
P2 = 100 kpa = 0.9869 atm
V2 = (P1V1 / T1) (T2 / P2) = (0.02302 * 0.14247 / 293.15) (273.15 / 0.9869)
V2 = 3.09647*10-3L
find n2 , V2 / Vstp = n2 / nstp
at STP 1 mole of gas occupies 22.4 L
(3.09647*10-3 / 22.4) = n2 / 1
n2 = 1.38235*10-4 mol
mass of condensed vapor = 101.3587-101.0450 = 0.3137 gm
Molar mass = mass of the condensed vapor / n2 = 0.3137gm/1.38235*10-4 mol =
Molar mass = 2269.323 gm/mol
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