1 L of a gass is at a pressure of 10 to the power -6 mm of hg at 25 degree cesius.how many molecules are in the vessel?

THINGS GIVEN

 

PRESSURE=10^-6mm of Hg

We know that 760mm of Hg=1 atm

 Therefore,10^-6 mm of Hg=(10^-6/760)atm=0.001316×10^-6 atm

volume=1litre

R=0.0821

T=(273+25)K=298K

 

Therefore,if the gas is assumed to be an ideal gas,then PV=nRT

n=PV/RT=(0.001316×10^-6)×1/(0.0821×298)=5.4×10^-11 moles

now,1mol of gas has 6.023×10²³ no. of molecules

therefore,5.4×10^-11 mol has 32.5242×10¹² molecules.