28 Mr. J. Kam on van tier Waals Equation and 



Where the values 



3V»« 



a 



p. 



(«) 



and 



and consequently V C = 3Z> are found, a and P c divide out, 

 and the density does not affect the result (as b here has the 

 meaning of @ in equations (2), (4) and (B)). 

 The expression 



Pc== 3v: 2 ' w 



resulting from (a), however, cannot be correct, and the 

 same consequently applies to 



P __ _^ QP 



X 1C TT 2 ° L CJ 



resulting from (c). 

 Hence the values 



4a 

 TT — P 4-P, — 4.P — - 



and 



IL= 



B . T c B . T c 3 B . T ( 



which result from this solution of the equation of van der 

 Waals, do not correspond as they should do. For the 



correction-factors =^ and b should cause the same increase 



of pressure on either side of the equation. 



On substitution of Y c =2b in equation (A) (or of V e =.3/2 

 in (B)), we obtain a quadratic equation. 



Multiplying and arranging according to powers of b, we 

 find for the critical state 



j2_R^. 6+ JL = o, . . . . (D) 



and thus , R.T. , / ( K . T, I * ~^~ 

 b= -W7 ± V l^FTJ -0P7 

 There is, however, only one value of b. Eence 



, E.T C , fR.TJ 2 a 



6 =TP7> and \TF7$ = 9IV 

 or 



6 2 = — 

 9P ' 



