Q9 of 100 Page 34

The density of an ideal gas is 1.25 × 10–3 g cm–3 at STP. Calculate the molecular weight of the gas.

We know ideal gas equation


PV=nRT


Where V= volume of gas


R=gas constant


T=temperature


n=number of moles of gas


P=pressure of gas


STP means standard temperature-273.15K and pressure 101.325 kPa.


Given:


T=273.15K


P=101.325Pa


Density of ideal gas 1.25 × 10–3 g cm–3


1gcm-3=103kgm3


kgm3


Number of moles n ==


Density


From ideal gas equation, we can write




Molecular weight of gas is 2.3810-2gmol-1


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