AQA GCSE Chemistry Paper 1 Practice Exam 2025 – Complete Study Resource

To convert a concentration from mol/dm³ to g/dm³, the correct approach involves using the equation: mass = moles x molar mass (Mr). When a substance's concentration is expressed in moles per cubic decimeter (mol/dm³), you can determine the mass in grams by multiplying the number of moles by the substance's molar mass, which is expressed in grams per mole (g/mol).

This correctly provides the mass of the solute in grams that is present in one cubic decimeter of solution. By applying this method, you effectively convert the concentration from molarity (in moles) to mass concentration (in grams), allowing for a practical measurement in laboratory settings.

Other methods may not accurately derive the mass in grams from concentration measured in moles. For instance, dividing the concentration by the molar mass does not yield the correct unit conversion, nor does simply adding the concentration to the volume convert the units appropriately. Thus, using the correct mathematical relationship of mass, moles, and molar mass is essential for this conversion.