Wednesday, June 1, 2011

Numerical Value of R and Units

(1).     At N. T. P
P   =  1atm,        T = 273K.
V  =   22.4 lit,   n = 1 mole.
R   =(P ×V)/ (n × T)   =  (1 atm. × 22.4 lit) / (1 mol  × 273K) =   0.821 atm lit deg-1 mol-1
Now a day’s at N. T. P        
P = 1bar   (At P = 1bar, Volume occupied by 1 mole is 22.7 lit instead of 22.4 lit at 1 atm.)
V = 22.7 lit,  
n = 1 mol.
T = 273K
R = (1 bar × 22.7 lit) / (1 mol × 273K) 
    =       0.083 bar lit mol–1 degree–1  
(2).     In C. G. S Units
P  = 76cm of Hg,  r of Hg  = 13.6 gm/ml            
P    =   ρhg
=   76 × 13.6 × 9.81 dynes/cm2
V     =   22400 ml
T     =   273 K
n     =    1mol
R   =   (76 × 13.6 ×9.81) × 22400 dynes/cm2× ml. × degree–1 mol–1
R   =    8.314 × 107 ergs degree–1 mol–1
(3).     In S. I Units
1 J  =   107 ergs.
R   =   8.314 J degree–1 mol–1
(4).     In terms of Calories
1 Cal.   =   4.18 J.
R    =  8.314/4.18  cal. degree–1 mol–1
      =   1.987 calories degree–1 mol–1

1 comment:

  1. information is explained in an easy way, so it is to learn

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