The article shows that the larger the size of the ions, the lower the electrostatic forces between the cations anions, causing the decline of their association and the electrical conductivity of the solution.
Electrical conductivity - one of the most easily of measurable properties of the system, you can choose the optimum temperature and concentration process conditions. Dependences of electrical conductivity the nature of the ions is evident (Table 1).
Table 1.
Dependence of the electrical conductivity of the nature of the ions
|
anion
kation |
Сl- |
Br - |
NO3- |
CO32- |
SO42- |
ClO4- |
SiF62- |
P2O74- |
PO43- |
OH- |
|
H+ |
- |
- |
0,471 |
- |
0,395 |
0,326 |
0,38 |
0,13 |
0,064 |
- |
|
Li+ |
- |
0,0847 |
0,0896 |
- |
0,0637 |
- |
- |
- |
- |
- |
|
Na+ |
0,1317 |
0,0865 |
0,0871 |
0,08 |
0,07136 |
- |
- |
- |
- |
0,31 |
|
K+ |
0,128 |
0,0976 |
0,0874 |
0,105 |
0,0906 |
- |
- |
- |
- |
0,4 |
|
Rb+ |
0,102 |
0,0654 |
0,0628 |
0,0652 |
- |
- |
- |
- |
0,32 |
|
|
Cs+ |
0,071 |
0,0561 |
0,0515 |
0,0547 |
0,0492 |
- |
- |
- |
- |
- |
|
Cu2+ |
- |
- |
- |
- |
0,0921 |
- |
- |
- |
- |
- |
|
Zn2+ |
- |
- |
- |
- |
0,0636 |
- |
- |
- |
- |
- |
|
Cd2+ |
- |
- |
- |
- |
0,0504 |
- |
- |
- |
- |
- |
Similar ranks can construct for other temperatures and concentrations. They are similar [1].
General patterns: in the concentration dependences of alkali halides maximum conductivity (at c ⃰) is shifted to high concentrations in the a number Na - K - Rb - Cs. The same is observed
from carbonates and alkali metal nitrates. So, at LiCl c ⃰ = 20%, CsBr с ⃰ = 40%;
K2CO3 at maximum corresponds to 40%, and Rb2SO3 and Cs2SO3 – 50%. At LiNO3 с ⃰ = 30%, at Rb2SO4 and Cs2SO4, as that of Na2WO4 and Na2MoO4 – no of maximum. At Na2CrO4 с ⃰ = 33%, a maximum of specific electrical conductivity H4P2O7 at 21%, and 60% at K4P2O7.
Thus, the larger the size ion the lower the electrostatic forces between the anions, cations, causing their association and downturn of the electrical conductivity of the solution.
Different effects of anions on the electrical conductivity depend on the number of oxygen atoms in them (Fig. 1).
Fig.1. the dependence of specific conductivity on the number of oxygen atoms in the anion
The more oxygen atoms, the less specific electrical conductivity, which is obviously associated with the formation of additional oxygen-hydrogen bonds. Can not but influence and the charge of the ion. But only spectral studies of systems can fully illuminate the influence of ions on the structure and the properties of solutions.
The work is submitted to the International Scientific Conference «Fundamental researches», Dominican Republic, April 13-22, 2014, came to the editorial office оn 26.03.2014