水-メタノール混合溶媒におけるアルカリ金属チオシアン酸塩の電気伝導度測定

抄録

The conductivity of several alkali metal thiocyanates in water-methanol mixtures was measured at 25°C. The data were analyzed using the Lee-Wheaton theory for symmetrical electrolytes to obtain ion association constant, K_A, limiting molar conductivity, Δ₀, and limiting ionic molar conductivity, λ₀^±. In all the solvent systems, calculated λ₀⁺ values of the alkali metal ions increase in the order Li⁺<Na⁺<K⁺<Rb⁺<Cs⁺. The.λ₀^± values of the alkali metal ions and thiocyanate ion showed a minimum whe n the molar fraction of methanol was ca.0.4. The changes in λ₀^± of these alkali metal ions and thiocyanate ion with the molar fraction of methanol agree with the change in the viscosity of the solvent or the heat of mixing of water-methanol mixtures. These alkali metal thiocyanates form little or no ion aggregated in water and water-methanol mixtures. These alkali metal thiocyanates were K_A=15-24 dm3 mol^-1 in methanol.