IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Glass Ball as Bullet Solubility System: Ammonium formate with Formic acid and Water

   (1) Ammonium formate; NH4CHO2; [540-69-2]  NIST Chemistry WebBook for detail
   (2) Formic acid; CH2O2; [64-18-6]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

   Tatiana Ageyeva and Oleg Golubchikov, Institute of Non-Aqueous Solutions Chemistry, Russian Academy of Sciences, Ivanovo, Russia, July, 1993.

Critical Evaluation:

6. Nonaqueous Metal Formate Systems

         The solubility of metal formates has been measured in water, organic and organic-water solvents, but most of the solubility data for metal formates has been obtained from systems in which water is the solvent. Of the organic solvents, formic acid is especially suited to serve as a solvent for the metal formates. However, the formates are less soluble in formic acid than in water. There are three exceptions to this statement: ammonium formate, lithium formate and sodium formate. The behavior of ammonium formate will here be considered separately from that of the other metal formates

6.1. Ammonium formate

Binary Systems

        (1) The NH4CHO2-HCHO2 system. Three publications1-3 present solubility data for ammonium formate in formic acid. The solubility data were obtained over a temperature range of 193.0 to 390 K. The values werre determined by the freezing point method. The data in two of the articles1,2 agree with each other to within 0 to 7%. The agreement improves as the temperature increases. There is agreement also with respect to the identity of the equilibrium solid phase. The difference in the solubility values is likely due to the fact that in one report1 the starting salt was NH4CHO2·HCHO2 but the solubility was calculated as due to NH4CHO2. Becker and Davidson3 studied the concentration-temperature equilibrium of the formic acid-ammonia system over a wide range of component concentrations. The data are presented only in graphical form in Becker and Davidson3 but the numerical data are also available.4 Because the data were obtained for a wide range of concentrations, they may be considered as representing two systems: NH4CHO2-HCHO2 and NH4CHO2-NH3. The data for the NH4CHO2-HCHO2 system is consistent with the data of Kendall and Adler.2 In our opinion, The data of these two studies are more reliable than the data presented by Groschuff.1 The reason for this estimate is that the data obtained in Kendall and Adler2 were obtained using NH4CHO2 as the starting material and these data have a smaller experimental error associated with them. As a result, the recommended value for the solubility of ammonium formate in formic acid at 298.2 K is 4.19 mol%. The equilibrium solid phase is NH4CHO2·HCHO2.

        (2) The NH4CHO2-NH3 system. The solubility of ammonium formate in ammonia has been reported by Lindenberg5 over a temperature range of 195 to 243 K and a pressure range of 0 to 1 atm. Only a graphical representation of the data is given. However, the concentration-temperature data of the system agree within about 4% of the data for this system by others. All the data are in agreement at temperatures below 213 K. The solubility of ammonium formate in ammonia at 237 K and 1 atm is given as 133.1 g NH4CHO2 in 100 g NH3 (Becker and Davidson3) and 123.1 g salt in 100 g NH3 (Lindenberg5). An equilibrium solid phase is NH4CHO2·3NH3. However, these data can only be classified as tentative because there are no independent data to confirm them.

Ternary Systems

        Groschuff1 has reported solubility data for the NH4CHO2-HCHO2-H2O system at 266.7 to 312.2 K. These values show that the solubility of ammonium formate decreases as the water content of the system increases. The values are classified as tentative because there is no other report of a solubility study of this system.

Experimental Data:   (Notes on the Nomenclature)

References: (Click a link to see its experimental data associated with the reference)

   1  Groschuff, E., Ber. 36, 4351 (1903).
   2  Kendall, J.; Adler, H., J. Am. Chem. Soc. 43, 1470 (1921).
   3  Becker, B.; Davidson, A.W., J. Am. Chem. Soc. 85, 157 (1963).
   4  University Microfilms, Inc., Ann Arbor, Mich, L.C. Card No Mic 60-893.
   5  Lindenberg, W., Z. Naturforsch. 22b, 1 (1967).