Ammonium hydrogen carbonate

Structural formula
General
Surname	Ammonium hydrogen carbonate
other names	Ammonium bicarbonate Deer horn salt E503ii
Molecular formula	NH 4 HCO 3
Brief description	white, crystalline powder with an ammonia-like odor
External identifiers / databases
CAS number 1066-33-7 EC number 213-911-5 ECHA InfoCard 100.012.647 PubChem 14013 Wikidata Q421123
properties
Molar mass	79.06 g mol −1
Physical state	firmly
density	1.58 g cm −3
Melting point	Decomposition from 60 ° C
solubility	good in water (220 g l −1 at 20 ° C) insoluble in ethanol
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302 P: 301 + 312-330
Thermodynamic properties
ΔH f 0	−849 kJ mol −1
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Ammonium hydrogen carbonate (including A mmonium b i c arbonat, ABC engine) is an ammonium salt of carbonic acid . It is the main component of staghorn salt .

Occurrence

In nature, ammonium hydrogen carbonate is found as the mineral teschemacherite , as well as in guano deposits on the west coast of Patagonia and on the Chincha Islands .

Extraction and presentation

It is manufactured by introducing carbon dioxide into concentrated ammonia solution at 35 to 40 ° C. The precipitated crystalline ammonium hydrogen carbonate is centrifuged off and dried at a temperature of 40.degree.

properties

Ammonium hydrogen carbonate forms colorless prismatic crystals that appear in a rhombic crystal lattice. The salt dissolves very well in water . The solubility increases with the temperature.

Solubility of ammonium hydrogen carbonate in water
temperature	in K	273.2	283.2	293.2	303.2	313.2	323.2	333.2
	in ° C	0	10	20th	30th	40	50	60
solubility	in%	10.6	13.9	17.8	22.1	26.8	31.6	37.2

The pH value of an aqueous solution (50 g / l at 20 ° C) is approx. 8. Even at room temperature, a slow breakdown into ammonia, carbon dioxide and water can be observed. The rate of disintegration increases sharply with increasing temperature.

${\displaystyle \mathrm {NH_{4}HCO_{3}\rightleftharpoons NH_{3}+\ H_{2}O+\ CO_{2}} }$

The decay can be quantified via the corresponding dissociation pressures.

Dissociation pressure of ammonium hydrogen carbonate
temperature	in K	298.6	307.4	313.9	318.2	323.2	329.0	332.5
	in ° C	25.45	34.25	40.75	45.05	50.05	55.85	59.35
pressure	in kPa	7.85	16.26	26.79	37.06	52.65	82.11	108.64

use

Since it has a defined composition, it is more suitable than deer horn salt as a raising agent ("ABC-Trieb" / baking powder) for the production of Christmas cookies such as gingerbread and speculoos in large-scale automated baking systems . It is approved in the EU as a food additive with the number E 503ii and comes on the market with the purest additive .

The ufo-shaped pieces of cake "American" owe their name to this raising agent . According to this controversial theory, these pieces of cake were originally called "ammonia cans". A baker is said to have exchanged this monstrous word for “Americans”. (other theories on this under Americans (pastries) )

In the People's Republic of China , ammonium hydrogen carbonate was previously used in large quantities as the most important nitrogen fertilizer . Production began in 1958 and took place in over 1000 small systems. In the meantime it has mainly been replaced by urea , but in 2012 the market share was still 17%.

Individual evidence

1. ↑ ^{a b c d e f g} Entry on ammonium hydrogen carbonate in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ ^{a b c} Entry on ammonium hydrogen carbonate. In: Römpp Online . Georg Thieme Verlag, accessed on October 14, 2014.
3. ↑ PAETEC Formula Collection Edition 2003, p. 116.
4. ↑ ^{a b} Brockhaus ABC chemistry. FA Brockhaus Verlag, Leipzig 1971, p. 73.
5. ↑ ^{a b c} K.-H. Zapp, K.-H. Wostbrock, M. Schäfer, K. Sato, H. Seiter, W. Zwick, R. Creutziger, H. Head: Ammonium Compounds. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag, Weinheim 2005. doi : 10.1002 / 14356007.a02_243 .
6. ↑ Ching-Kwei Li, Rong-Yen Chen: Ammonium bicarbonate used as a nitrogen fertilizer in China . In: Fertilizer Research . tape 1 , no. 3 , 1980, p. 125-136 , doi : 10.1007 / BF01053127 .
7. ↑ Yara Fertilizer Industry Handbook 2014 ( Memento from May 17, 2017 in the Internet Archive ), p. 25.