Question

A)Calculate the density of NO2 gas at 0.990 atm and 36 ∘C. B)Calculate the molar mass of a gas if 2.50 g occupies 0.865 L at 680 torr and 36 ∘C.

Answer 1

Apply Ideal Gas Law,

PV = nRT

where

P = absolute pressure; V = total volume of gas

n = moles of gas

T = absolute Temperature; R = ideal gas constant

D = mass / volume and Molar volume = n/V

MW = molar weight of sample

Then,

PV = nRT; get molar volume

n/V = P/(RT)

get mass -> n = mass/MW

mass/(MW*V) = P/(RT)

D = mass/V

D/MW = P/(RT)

D = P*MW/(RT)

D = (0.99)(46)/(0.082*(36+273))

D = 1.797g/L

b)

molar mass of a gas --> MM = mass/mol

PV = nRT

n = PV/(RT) = 680*0.865/(62.4*(36+273)) = 0.03050

MM = mass/mol = 2.5/0.03050 = 81.967 g /mol