The assembled equipment is inserted into hypotonic, hypertonic, and isotonic solutions and the level on the capillary rises, falls, or stays level accordingly. This apparatus is easy for school children to use, but is fiddly to set up. It can be set up by a technician in advance.
Table of contents |
2 Setting up the Apparatus 3 Method of Use 4 Storage of the Apparatus 5 See Also |
B) Slide the rubber band to the top of the capillary level in order to mark the start position.Put the apparatus into 2.0M sucrose solution (hypertonic). The level in the capillary tube will fall as the water inside passes through the visking tubing in order to dilute the stronger solution outside.
C) Put the apparatus into distilled water (hypotonic). The level in the capillary tube will rise as the water passes into the visking bag to dilute the stronger solution inside.
The apparatus cannot be stored for more than a few days with the sugar solution inside, because it will go mouldy. The capillary tube should be removed and thoroughly rinsed as any sugar left inside will harden and block the tube. The visking bags can be left attached to the bungs but should be rinsed and stored in water or a mixture of water and ethanol to keep the bag soft. If the visking dries out it may become brittle and crack.Apparatus
Apparatus for
demonstrating osmosis
(assembled)Setting up the Apparatus
Method of Use
A) Clamp the apparatus in a retort stand, then place into a large beaker of 0.5M sucrose (isotonic). Make sure the visking bag is hanging freely in the solution. I.e. not touching the sides or bottom. This stops it from being squashed and distorting the results.Storage of the Apparatus