Visking Tubing, 30m Size 2

Visking Tubing (Dialysis Tubing), 30m Size 2

Visking tubing, also known as dialysis tubing, is used in school biology experiments as a model for a partially permeable membrane, such as a cell membrane or the lining of the small intestine. Its small pores allow small molecules like water and glucose to pass through and block larger molecules such as starch, which is why it is used to demonstrate diffusion and osmosis.

Demonstrating osmosis

A length of tubing is filled with a concentrated sugar solution (for example sucrose), sealed and placed in a beaker of distilled water. Water moves by osmosis from the dilute solution to the concentrated solution across the membrane, so the tubing swells and gains mass.

Demonstrating diffusion

A mixture of glucose and starch solution is placed inside the tubing, which is then submerged in a beaker of water. After a period, the water outside the tubing is tested. Glucose is detected, having diffused out through the pores. Starch is not detected, because its molecules are too large to pass through the membrane.

Modelling absorption in the gut

The diffusion experiment also models absorption in the small intestine, where small digested food molecules like glucose pass into the bloodstream and large undigested molecules like starch remain inside.

In life sciences research, the tubing is also used to purify samples by removing small molecules from larger ones.

Specification

• Length: 30 metres
• Size 2, 14.3mm inflated diameter
• Product of India