Reversablity of dehydration Aqueous magnesium bicarbonate when evaporated decomposes into magnesium carbonate. Is that reaction reversible by dissolving the carbonate in soda water?
Yes, in fact this process is similar to the processes in lime stone that form cave stalagmite and stalactites but with calcium carbonates.
$$\ce{M(HCO3)2 &lt;-&gt; MCO3 + H2O + CO2 }$$
$$\ce{M} = (\ce{Mg},\ce{Ca})$$
Though I should note the process in not called dehydration.