Two New Standards for the pH Scale.
- 1 January 1969
- journal article
- Published by National Institute of Standards and Technology (NIST) in Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
- Vol. 73 (1) , 37-41
- https://doi.org/10.6028/jres.073A.004
Abstract
Two new primary standards for the NBS pH scale, supplementing the five already available, are proposed. The new reference solutions are the 0.05 molal solution of potassium dihydrogen citrate and a mixture of sodium bicarbonate and sodium carbonate, each 0.025 molal. The citrate solution has a pH of 3.776 at 25 °C and is more stable under certain conditions than either the tartrate or phthalate standards. The carbonate solution has a pH of 10.012 at 25 °C. It therefore extends the NBS pH scale above its present upper limit of 9.180 at this temperature. Reference values pH(S), based on emf measurements of cells with hydrogen electrodes and silver-silver chloride electrodes, have been assigned to these two standard solutions at 11 temperatures from 0 to 50 °C.Keywords
This publication has 1 reference indexed in Scilit:
- Purification of sodium chloride and potassium chloride for use in electrochemical work, and the determination of small amounts of bromideJournal of Research of the National Bureau of Standards, 1946