I'm trying to make stock solution of 3M sucrose in water. In 25ml, this is 25.672g sucrose (FW 342.3). However, that mass of sucrose, in the powder, occupies a pretty substantial volume, such that if I add 25ml of water to it, I end up with a dissolved solution ~42ml in volume (it is fully dissolved). Puzzled by this, I've also prepared a second solution in which I am only adding water up to the 25ml line in my 50ml conical (so far only 9ml). This is obviously struggling to dissolve as the saturation solubility for sucrose is like 5M or something like that.
So what's the deal? Is my 40ml solution with the correct mass of solute and volume of solvent really 3M? My head says yes but my gut is uneasy.