LOWER TEMPERATURE LIMIT OF NBS (DIN) PH STANDARD BUFFER SOLUTION POTASSIUM TETROXALATE

NBS pH standard buffer solution 0.05 m potassium tetroxalate with assigned pH(S) between 0 and 95°C is saturated at 5°C. The temperature dependence of pH of the saturated solution differs noticeably from that of pH(S). Similarly, 0.1 m tetroxalate with assigned pH(S) between 15 and 60°C is saturated at 22°C. Additional experiments indicate that the extrapolation method of determining pH(S) allowed to obtain pH(S) values below the saturating temperatures although the pure supersaturated solutions cannot be obtained. © 1979.