Magnesium bicarbonate does not exist as a stable compound.

Here's why:

* Bicarbonate (HCO₃⁻) is unstable in solution. It readily decomposes into carbon dioxide (CO₂), water (H₂O), and carbonate ions (CO₃²⁻).

* Magnesium (Mg²⁺) ions react with carbonate ions. This reaction forms magnesium carbonate (MgCO₃), a solid compound.

Therefore, when magnesium ions and bicarbonate ions are present in solution, the following reaction takes place:

Mg²⁺(aq) + 2HCO₃⁻(aq) → MgCO₃(s) + CO₂(g) + H₂O(l)

So, there is no molecular weight for magnesium bicarbonate because it doesn't exist as a distinct compound.