HYDROGEN INTO ATOMS 17^ 



thinking that E must be greater than the lower Hmit, whereas there i . 

 evidence that it is considerably less than the upper limit. The most prol 

 able value of E is therefore obtained by placing ai = i in (53). The value 

 thus obtained is, however, almost identical with the value of C given by 

 (46). We have seen from (43) that the mathematical treatment is much 

 simplified if C = E. The small difiference between 0.0048 and 0.0046 is 

 well within the experimental error, so that for convenience we may place 



C = E = o.oo48VTa. (54) 



CALCULATION OF K FROM LOW PRESSURE DATA 



By the aid of these values of C and E we may calculate K from (43) 

 We have seen that at high temperatures B is less than 0.008. Taking 

 Equation 32 into consideration, we may thus conclude that B must always 

 be less than o.47/VTa- At very low pressures T^ = 300, so that under 

 these conditions B might be as large as 0.027. At similarly low pressures 

 E = 0.083. At a pressure P == 0.207 the term BP in (42) is less than 

 0.005 si^d may be neglected as compared to E in calculating E. We may 

 thus calculate K from (43) without knowing the value of B, provided w^e 

 use the data at pressures of 0.207 mm. and lower. 



Table IX gives the results of such calculations from the data at the 

 lowest pressures. The values of K were calculated from the corresponding 

 values of W^^ by Equation 43, placing F = E. At 0.015 and 0.039 "^i"'''- 

 pressure, Tq was placed equal to 300°, but at 0.207 mm. the values of T„ 

 used in the calculation were those given in the next, to the last column of 

 the table. 



TABLE IX 

 Dissociation Constant of Hydrogen from Low Pressure Data 



