Calcium magnesium acetate

Structural formula
${\displaystyle \mathrm {x\ Ca^{2+}\ y\ Mg^{2+}\ 2(x+y)\ CH_{3}COO^{-}} }$
General
Surname	Calcium magnesium acetate
Molecular formula	Ca x Mg y (CH 3 COO) 2 (x + y)
External identifiers / databases
CAS number 76123-46-1 110518-63-3 PubChem 13981837 Wikidata Q906716
properties
Molar mass	123.44 g mol −1 (for 1 Ca and 1 Mg)
Physical state	firmly
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Calcium magnesium acetate (Ca _x Mg _y (CH ₃ COO) _{2 (x + y)} ) is an alternative road salt .

Extraction and presentation

The calcium magnesium acetate used as a scattering agent shows a fluctuating Ca: Mg ratio, as in the dolomite used as raw material, between about 1: 1 and 3: 7. The dolomite is heated to a high temperature ("burned") in order to drive off the carbonates as carbon dioxide . The resulting oxide is then reacted with acetic acid. The detour via burning is necessary because native dolomite is only attacked very slowly, even by much stronger acids (e.g. hydrochloric acid ).

${\displaystyle \mathrm {Ca_{x}Mg_{y}(CO_{3})_{2(x+y)}\longrightarrow } }$ ${\displaystyle \mathrm {2(x+y)\ CO_{2}\uparrow +x\ CaO+y\ MgO} }$

Burning reaction

${\displaystyle \mathrm {x\ CaO+y\ MgO+2(x+y)\ CH_{3}COOH\longrightarrow } }$ ${\displaystyle \mathrm {Ca_{x}Mg_{y}(CH_{3}COO)_{2(x+y)}+(x+y)\ H_{2}O} }$

Implementation with acetic acid

use

advantages

In contrast to sodium chloride, calcium magnesium acetate does not damage bridges or trees. The negatively charged acetate ions , which replace the more aggressive chloride , are primarily responsible for this . Calcium and magnesium also serve as nutrients for plants. In a test in the city of Halle (Saale) , calcium magnesium acetate was able to demonstrate a low level of particulate matter binding .

disadvantage

Calcium magnesium acetate is about ten to twenty times as expensive as normal road salt made from sodium chloride and is therefore not competitive. Furthermore, it does not have a melting effect, but merely facilitates the mechanical removal of the snow by preventing the caking. For safety reasons, calcium magnesium acetate must not be applied to the places where tram tracks run in the road bed.

literature

• John Emsley: Sun, Sex and Chocolate. More chemistry in everyday life . Wiley-VCH, Weinheim 2003, ISBN 3-527-30790-7 .

Individual evidence

1. ↑ ^{a b} MSDS ( Memento from May 3, 2013 in the Internet Archive ) (PDF; 23 kB).
2. ↑ Patent US5430185 : Process for manufacturing crystalline calcium magnesium acetate. ‌
3. ↑ A hot topic of ice and snow: How to keep roads and sidewalks usable and safe in winter without unnecessarily polluting the environment. (PDF; 229 kB).
4. ↑ ^{a b} Torsten Bayer, Katrin Eifert, Christian Ehrlich, Ulrich Zimmermann, Wigbert Albrecht, Silke Jacobi: Trial use of calcium magnesium acetate (CMA) to reduce traffic-related fine dust emissions in Halle (Saale) . Hazardous substances - cleanliness. Luft , 71 (2011) No. 5, pp. 221-226.