Why does a stalk of celery wilt when placed in glass salt water?

When a stalk of celery is placed in a glass of salt water, it wilts because of a process called osmosis. Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration through a semipermeable membrane. In this case, the semipermeable membrane is the cell membrane of the celery cells.

The salt water creates a hypertonic solution, which means that there is a higher concentration of solute (salt) outside of the celery cells than inside. This causes the water molecules inside the celery cells to move out of the cells and into the salt water, in order to equalize the concentration. As a result, the celery cells lose their turgidity and the stalk of celery wilts.

The rate of wilting can be affected by the concentration of the salt water. The more concentrated the salt water, the faster the celery will wilt.