Does solubility differ from molar solubility?
They differ only in the units used to measure them.
Scientists use many different units to express the solubility of a substance.
Usually, the solubility is listed as grams of solute per 100 g of solvent.
For example, the solubility of sodium chloride is 35.7 g/100 g of water at 20°C.
But you can use other units to express solubility such as g/100 mL and g/L.
Molar solubility is the number of moles of the solute that can dissolve per litre of solution before the solution becomes saturated.
The density of a saturated NaCl solution is 1.202 g/mL. What is the molar solubility of NaCl?
Assume that you have 35.7 g NaCl in 100 g of water. Then you have 135.7 g of solution.
Moles of NaCl = 35.7 g NaCl ×
Volume of solution = 135.7 g solution ×
Thus, the molar solubility of NaCl in water at 20 °C is 5.41 mol/L.