Ganciarov Mihaela, Stoica Rusandica, Josceanu Ana Maria
Analysis Department, National Institute of Chemistry and Petrochemistry R&D of Bucharest, 202 Splaiul Indepentei Street, 060021 Bucharest, Romania.
Department of Analytical Chemistry and Environmental Engineering, National University of Sciences and Technology Politehnica Bucharest, 1-5 Polizu Street, Sector 1, 011061 Bucharest, Romania.
Molecules. 2023 Sep 26;28(19):6813. doi: 10.3390/molecules28196813.
The ionic association constants of sodium with carbonate ion (K1C') and acidic carbonate ions (K2C') were measured in NaCl-NaHCO-HO ternary systems to determine the distribution of sodium among the chemical species present in the growth medium of algae. The mean activity coefficients of sodium chloride (in pure sodium chloride and in a mixture of electrolytes) were determined experimentally using two electrochemical cells, namely Ag, AgCl| KCl (3 M)|| NHNO (1 M)| NaCl (mNaCl)| Na-ISE and Ag, AgCl|KCl (3 M)|| NHNO (1 M)| NaCl (mNaCl)| Cl-ISE. The studies carried out show that the values of the association constants of K1C' and K2C' do not depend on the composition of the medium, but only on the effective ionic strength. The experimentally obtained γNaCl0 values in the binary system are comparable to the mean activity coefficients values for NaCl, calculated using data from the literature, with -0.9 to 0.1% relative standard deviation. The obtained results show that the experimentally determined mean activity coefficient in the ternary system, γNaCl, is smaller than γNaCl0 in the binary system over the entire field of ionic strengths studied. The ternary system NaCl-NaHCO-HO obeys Harned's rule.
在NaCl-NaHCO₃-H₂O三元体系中测量了钠与碳酸根离子（K₁C'）和碳酸氢根离子（K₂C'）的离子缔合常数，以确定藻类生长培养基中存在的化学物种间钠的分布。使用两个电化学电池，即Ag, AgCl|KCl (3 M)||NH₄NO₃ (1 M)|NaCl (mNaCl)|Na-ISE和Ag, AgCl|KCl (3 M)||NH₄NO₃ (1 M)|NaCl (mNaCl)|Cl-ISE，通过实验测定了氯化钠（在纯氯化钠和电解质混合物中）的平均活度系数。开展的研究表明，K₁C'和K₂C'的缔合常数的值不取决于介质的组成，而仅取决于有效离子强度。二元体系中实验获得的γNaCl⁰值与使用文献数据计算得到的NaCl平均活度系数值相当，相对标准偏差为-0.9%至0.1%。所得结果表明，在整个研究的离子强度范围内，三元体系中实验测定的平均活度系数γNaCl小于二元体系中的γNaCl⁰。三元体系NaCl-NaHCO₃-H₂O遵循哈纳德规则。
