What mass in #"mg"# of #"O"_2# gas is found in #"469.9 mL"# of it contained at #"755 mm Hg"# and #60^@ "C"#?
1 Answer
The Creative Chemist spots the volume
He thus pulls out the ideal gas law from out of nowhere (presumably some textbook from underneath his dusty study desk), and carefully examines the units.
#PV = nRT#
He is unfazed by the volume and pressure units of
Looking only for the mass of the gas, he filters out the rest and realizes that the mols are:
#n = (PV)/(RT)#
and thus that the mass is merely the molar mass
#nM = m = (PMV)/(RT)#
He is admittedly too lazy to use the universal gas constant in any other units than
#color(blue)(m_(O_2(g))) = ((755 cancel"mm Hg" xx cancel"1 atm"/(760 cancel"torr"))("31.998 g/"cancel"mol")(469.9 cancel"mL" xx cancel"1 L"/(1000 cancel"mL")))/((0.082057 cancel"L"cdotcancel"atm""/"cancel"mol"cdotcancel"K")(60 + 273.15 cancel"K"))#
#=# #color(blue)("0.546 g O"_2(g))#
He is feeling nice enough to give the mass in
#=# #"546 mg"#