The dissociation constant for potassium methylamide ion pairs in methylamine

Abstract

The limiting equivalent conductance (Λ0) and ion pair dissociation constant (Kd) have been obtained for potassium methylamide in methylamine from conductance data measured over the temperature range −55 to + 25° C. The value of Kd increases from 6.3 × 10−8 mol L−1 at the highest temperature to 9.4 × 10−7 mol L−1 at the lower limit. The results show good agreement with literature data for potassium amide in ammonia after corrections for differences in solvent viscosity and dielectric constant. The heat of dissociation is −26 kJ mol−1 above −15 °C, but decreases gradually at progressively lower temperatures as a shift occurs from tight to loose ion pair structures.