An experiment shows that a 252 mL gas sample has a mass of 0.433 g at a pressure of 760 mm Hg and a temperature of 34 degrees C. What is the molar mass of the gas?

1 Answer
Pitufox27
Dec 2, 2016

Molar mass is #43.3 color(white) {.}g cdot mol^{- 1}#.

Explanation:

Gas law's shows that:

#p cdot V = n cdot R cdot T#,

where #p# is the pressure of gas, #V# it's volume, #n# the amount of gas, in mols, #R# is the constant of gases, and #T# is the absolute temperature of the gas.

In I.S. units, #R approx 8.31 color(white) {.} J cdot mol^{- 1} cdot K^{- 1}#.

Done molar mass is given by:

#M_r = m/n#

we can write gas law's in the next form:

#p cdot V = m/M_r cdot R cdot T#,

and we obtain:

#M_r = {m cdot R cdot T}/{p cdot V} = {0.433 g cdot 8.31 J cdot mol^{- 1} cdot K^{- 1} cdot (34 + 273,15) K}/{760/760 cdot 1.013 cdot 10^5 Pa cdot 252 cdot 10^{- 6} m^3} =#
#= 43.3 g cdot mol^{- 1}#

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