318 GASOMETRIC-VOLUMETRIC METHODS 



droplet and Vc the volume of gas in the compensation chamber and 

 capillary up to the index droplet. When Ad is negligibly small with 

 respect to Vc, the expression may be reduced to: 



AVp„ = nAd 



Conversion of (ATpJ to standard conditions is carried out in the 

 usual manner. 



The preceding equations do not take into account the volume of 

 gas which may be dissolved in the liquid. For carbon dioxide the 

 following relation obtains at temperature t: 



CO2 (dissolved) = ( ,, ^^\) j PraC02,-Vln 



Wr + Ad/ 



where Vr is the volume of gas in the reaction chamber plus the 

 volume in the capillary up to the index droplet. P/ is the total gas 



pressure in the reaction chamber, a C02< is the solubility coefficient 

 of carbon dioxide for the liquid at temperature t and one atmosphere 

 pressure of carbon dioxide (vol. gas at S.T.P./vol. liquid), and VIr 

 is the volume of liquid in the reaction chamber. 



If the precision of the measurements merits corrections for dis- 

 solved oxygen and nitrogen in the liquid, additional formulae may 

 be applied. Thus the volume of oxygen or nitrogen forced into solu- 

 tion by compression of gas in the compensation chamber during the 

 experiment equals: 



AO2 (dissolved) = a O^^-Vk-Po, ( 



P_f 

 Po 



1 (a) 



AN2 (dissolved) = a N2 -R-Pn. (^^ - 1 ) (&) 



t 



vPo 



where a O21 and a N2t are the solubility coefficients of the respective 

 gases in the liquid at temperature t, Vic is the volume of liquid in 



the compensation chamber, P02 and P^j are the initial partial pres- 

 sures of the respective gases (in calculating these values one should 

 not forget to consider the aqueous tension), and P/ is the final 

 pressure of the system. These equations are based on the fact that 

 the partial pressures of the gases in the compensation chamber have 

 increased to (P//Po) times their original values. Since the partial 

 pressures of the gases in the reaction chamber have decreased to 



