Started the solubility of solids half of the experiement. It took nearly an hour for the solution to reach the saturation point. I now have a magnetic stirrer but I may need to rethink this side of the experiment. I don't have enough time to do this 12 times.
I know that 25g of sodium chloride will dissolve into water at room temperature, so, rather than adding the sodium chloride in 5g intervals, I can add most of it in one go. I can then leave it on the magnetic stirrer and complete another aspect of the investigation.