University Chemistry ›› 2017, Vol. 32 ›› Issue (11): 45-50.doi: 10.3866/PKU.DXHX201706031

• Chemistry Laboratory • Previous Articles     Next Articles

Influence of the Shape of Transfer Tube on Determining Ion Transference Number by Hittorf Method

Jin-Yue YANG,Jing ZHU,Wei GAO,Yuan CHUN*()   

  • Published:2017-11-17
  • Contact: Yuan CHUN E-mail:ychun@nju.edu.cn
  • Supported by:
    江苏高校品牌专业建设工程项目;南京大学“十三五”实验教学改革研究课题

Abstract:

In physical chemistry experiment, straight and U-shaped transfer tubes are often used for determining Cu2+ ion transference number by Hittorf method. When a U-shaped transfer tube is used, the result calculated from the concentration change of cathode chamber solution usually has a significant error. The concentration distributions of CuSO4 solution with height in the straight, U and nshaped transfer tubes after electrolysis were investigated via spectrophotometry, using CuSO4 and Cu hoops as electrolyte and electrodes, respectively. It is found that the shape of transfer tube has a great effect on the concentration of central chamber solution. Because the cathode locates at the bottom of the U-shaped and n-shaped transfer tubes, the concentration of central chamber solution changes a lot after electrolysis due to convection caused by the gravity effect, and the concentration of cathode chamber solution is also affected. It would bring a significant error to the measurement of ion transference number. Contrarily, this effect is ignorable if a straight-shaped transfer tube is used, and thus more accurate result can be obtained.

Key words: Physical chemistry experiment, Ion transference number, Hittorf method, Shape of transfer tube

MSC2000: 

  • G64