Consider the following date gathered in a \"Molar Mass of a Gas\" experiment. *

ID: 558068 • Letter: C

Question

Consider the following date gathered in a "Molar Mass of a Gas" experiment.

* Mass of the empty reaction test tube: _____27.54_____ g

* Mass of the test tube and MnO2 used in the reaction: ____28.04___ g

* Mass of the test tube, KClO3 (MM = 122.55 g/mol) and MnO2 used in the reaction: ____29.31___ g

* Mass of the test tube and its contents after the reaction: ____28.83_____ g

* Volume of the bubble of oxygen generated in the experiment: ___ (3.60x10^2) ___ mL

* Atmospheric pressure in the lab: ______ (7.4380x10^2) ______ mm Hg

* Vapor pressure at reaction temperature: _____18.6_____ mm Hg

* Temperature: ____21.0____ deg. C

Calculate the experimental molar mass of dry oxygen under those conditions.

mass of Oxygen = (29.31-28.83) = 0.48 g

for moles of O2:

PV = nRT

n = PV/(RT)

Pgas = PTotal - Pvapor = 743.80 - 18.6 = 725.2

n = PV/(RT)

n = 725.2*(0.360)/(62.4*(273+21))

n = 0.014230

MM = mass of O2 / moles of O2 = 0.48 /0.014230 =33.73 g/mol

accepted values is 32 g/mol

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