which substances are moving into the dialysis bag and which are moving out of the dialysis bag?
They diffused, as there was a concentration gradient. If the solutes moved into the bag, then the outside of the bag was hypertonic, containing a higher solute concentration than that of the solution inside of the bag. This happens because the solutes attemp to always move down their concentration gradients, into an area where other molecule of the solute are more rare. Example. think of puring water into a table. If the water didnt go to an area of a lower concentration, then it would remain in the shape of the cup. But since the water DOES move to an area of lower concentration, it will soread around the table.