Question: what is the formula to find molar solubility?
Answer: Divide the mass of the dissolved compound by its molar mass to calculate the number of moles. In our example, this would be: Number of moles (NaNO3)=21.9g /85 g/mole= 0.258 moles. Divide the number of moles by the solution volume in liters to calculate solubility in mole/L.