Question

A sample of gas at 25ºc has a volume of 11 l and exerts a pressure of 660 mm hg. how many moles of gas are in the sample?

Answer 1

  The  moles of  the gas    in the sample  is 0.391  moles

    calculation
by use  of  ideal  gas  equation, that  is Pv=nRT
where  n  is number  of moles
           P(pressure)= 660  mmhg
           R(gas  constant)  =  62.364 l.mmhg/mol.K
           T(temperature)= 25 +273 =   298 k

by  making  n  the subject of the  formula

n= Pv/ RT

n is therefore=   (660mm hg  x11 L)/(  62.364 L.mmhg/mol.k  x298 K)  = 0.391  moles