Guys, pls help me. In product, i got CaHCO3 and it turned out that it dissociates to CO2 and other compounds. So, is there also such compounds which dissociate? I mean i want to learn to predict the products of the reaction and I had such problem. Any rules on that topic? Sorry, I am not good at chem
Ca(HCO3)2 generally dissociates to CO2, H2O, and CaCO3 through evaporation. your Ca(HCO3)2 would not be a product, it would be an aqueous reactant. In a decomposition reaction, there is only one reactant, and it forms several products.
Hope this helps
I suppose that you mean Ca(HCO3)2, calcium bicarbonate. That is a hypothetical compound that has not been isolated in solid form.
One can have a stable water solution of Ca++ ions, bicarbonate ions HCO3−, carbonate ions CO3−− and dissolved CO2, provided that the CO2 is not allowed to escape (or there is enough CO2 in the gas above the liquid) and the concentration of the other ions is low enough. The main equilibrium reaction is
2 HCO3− CO2 + H2O + CO3−−
When calcium carbonate is added to water with some CO2, the reaction goes to the right and some of the CaCO3 dissolves
However, when one tries to evaporate that solution, the CO2 evaporates too while it becomes easier for two bicarbonates to meet; and thus the above equilibrium shifts to the right, well before any calcium bicarbonate could crystallize. Eventually what crustallyzes is calcium carbonate, which is stable.
This how stalagmites and stalactites form in caves, and travertine forms in hot springs.
Op · 1y
Hypothetical compound is the term that I was looking for. I got it. Thank u very much
· 1y · edited 1y
Calcium hydrogencarbonate, Ca(HCO3)2, was never prepared pure. It's just a name for a mixture that's stable at rather narrow range of temperature, concentration, acidity. It's one of the things you have to learn for now, since underlying mechanisms are quite complex.
Op · 1y
You could start by looking up the correct empirical formula for calcium bicarbonate. Calcium ion has a +2 charge.
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