Suppose you had a balloon made of some highly flexible semipermeable membrane. The balloon is filled completely with a 0.2 M solution of some solute and is submerged in a 0.1 M solution of the same solute:
Initially, the volume of solution in the balloon is 0.25 L. Assuming the volume outside the semipermeable membrane is large, as the illustration shows, what would you expect for the solution volume inside the balloon once the system has come to equilibrium through osmosis? [Section 13.5]

Key Concepts

Osmosis

Osmosis is the movement of solvent molecules through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. This process continues until equilibrium is reached, where the concentrations on both sides of the membrane become equal. In this scenario, water will move from the 0.1 M solution outside the balloon into the 0.2 M solution inside, increasing the volume inside the balloon.

Concentration Gradient

A concentration gradient refers to the difference in the concentration of a substance between two areas. In this case, the gradient exists between the 0.2 M solution inside the balloon and the 0.1 M solution outside. The movement of water during osmosis is driven by this gradient, as the system seeks to equalize solute concentrations across the membrane.

Equilibrium

Equilibrium in a chemical system occurs when the rates of forward and reverse processes are equal, resulting in no net change in concentration. For osmosis, equilibrium is achieved when the concentrations of solute on both sides of the semipermeable membrane are equal. In this example, the volume of the solution inside the balloon will increase until the solute concentrations inside and outside the balloon are balanced.