Chemical solubility

Question

How does a solute (dextrose) negatively impact the solubility of another solute (plant peptone) in water; thereby causing the peptone (which is close to its solubility limit) to precipitate.

Answer 1

Hello Alicia!

Using laymen terms, think like that:

When plant peptone was dissolved, water was bound to it. Then dextrose came, and water likes dextrose more, so it abandoned plant peptone, letting it sink to bound with dextrose.

Now using more appropriate terms:

The dextrose changes the water activity in the new solution, so this new activity water has less affinity with plant peptone.

Answer 2

The water can only hold a certain amount of dissolved material. Since dextrose is relatively soluble, it interferes with the solubility of other, less soluble solutes such as plant peptone.