Two beakers, one with pure water (blue) and the other with a solution of NaCl in water (green), are placed in a closed container as represented by drawing (a). Which of the draw- ings (b)–(d) represents what the beakers will look like after a substantial amount of time has passed?

Verified step by step guidance

1. Identify the initial conditions: one beaker contains pure water (blue) and the other contains a NaCl solution (green).
2. Understand the concept of osmosis: water will move from the area of lower solute concentration (pure water) to the area of higher solute concentration (NaCl solution) through a semipermeable membrane.
3. Recognize that in a closed container, the water vapor will equilibrate between the two beakers over time.
4. Determine that the beaker with pure water will lose water, and the beaker with the NaCl solution will gain water.
5. Compare the final states of the beakers in the images provided: the correct drawing will show the beaker with pure water having less water and the beaker with NaCl solution having more water.

Key Concepts

Diffusion

Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration. In the context of the beakers, the NaCl solution will gradually mix with the pure water due to the movement of salt ions and water molecules, leading to a uniform concentration over time.

Equilibrium

Equilibrium in a chemical context refers to the state where the concentrations of reactants and products remain constant over time. In this scenario, after sufficient time, the concentrations of NaCl and water will reach a point where the rate of diffusion into and out of the beakers is balanced, resulting in a stable mixture.

Concentration Gradient

A concentration gradient exists when there is a difference in concentration of a substance across a space. In this experiment, the gradient between the pure water and the NaCl solution drives the diffusion process, as the salt ions move from the area of higher concentration (NaCl solution) to the area of lower concentration (pure water) until equilibrium is achieved.