CONTRIBUTIONS FROM THE RESEARCH LABORATORY OF 



PHYSICAL CHEMISTRY OF THE MASSACHUSETTS 



INSTITUTE OF TECHNOLOGY. — No. 2. 



THE ELECTRICAL CONDUCTIVITY OF VERY DILUTE 

 HYDROCHLORIC AND NITRIC ACID SOLUTIONS.* 



By H. M. Goodwin and R. Haskell. 



Presented May 11, 1904. Received June 30, 1904. 



CONTENTS. 



I. Purpose of the Investigation 399 



II. Preparation of the Solutions 400 



III. Tlie Conductivity Apparatus and Method of Measurement 401 



IV. Methods of Correcting for Impurities in Water at Great Dilution . . 403 

 V. The Conductivity Data 407 



VI. The Corrected Values of the Equivalent Conductivity 412 



VII. Summary 414 



I. Purpose of the Investigatiox. 



It is Avell known that there is great difficulty in obtaining an exact 

 value for the equivalent conductivity of completely dissociated acids, 

 owing to the large effect of the impurities of the water on the conductiv- 

 ity of even strong acids in very dilute solutions. These give rise to a 

 maximum value of the conductivity at a dilution of from 500 to 2000 

 liters, and to a marked decrease in its value at greater dilutions. Yet a 

 knowledge of the theoretical limiting value is of great importance, .since 

 upon it is based the assumed value of the equivalent conductivity of the 

 hydrogen ion and the calculated degrees of dissociation of acids in 

 general. 



Kohlrauschf in 1898 derived values for the conductivity of strong 

 acids at extreme dilution by adding to the observed value at 0.001 nor- 

 mal a quantity equal to the product of the observed increase between 

 0.001 and 0.00001 normal in the case of neutral salts by the ratio of the 



* The following investigation has been made possible through financial aid ex- 

 tended by the Trustees of tlie Wm. E. Hale Research Fund, 

 t Wied. Ann., 66, 794 (1898). 



