General Catalogue Chemistry - BECO Internacional LTDA.

special topics
667 199
Dialysis tubing
Replacement for the osmosis demonstration
apparatus (> 667 509 ).
Diameter: 18 mm
Length: 1 m
Diffusion
667 495
Gas diffusion apparatus
For demonstrating the various rates of diffusion
of different gases (e.g. hydrogen, CO 2 or air)
using a clay cylinder.
Light gases, such as hydrogen or helium (e.g.
from Minican gas cans), diffuse through a ceramic
cylinder quickly and cause an overpressure
in the Erlenmeyer flask, which is indicated by a
small jet of water.
Without stand material.
Scope of delivery
1 Erlenmeyer flask 664 244
1 Rubber stopper with two holes 667 269
1 Glass angle tube with nozzle 665 238
1 Glass tube 180 x 8 mm
1 Rubber stopper with one hole 664 132
1 Beaker, 600 ml
1 Ceramic cylinder
>
See pages 280 for gases
667 509
124 LEYBOLD DIDACTIC · GENERAL CATALOGUE CHEMISTRY
Osmosis demonstration apparatus
For demonstration and measurement of osmotic
pressure. The inner section of the apparatus
is filled with a saline or sugar solution, the outer
part with distilled water. The water diffuses into
the inner container through the semi-permeable
dialysis tubing, making the solution rise in
the capillary until the hydrostatic pressure
generated equals the osmotic pressure.
Scope of delivery
1 Test tube SB 29, with side arm
1 Capillary tube, 400 mm long, 8 mm dia.
1 Rubber stopper, SB 29 with 1 hole
1 Rubber stopper, SB 19 with 1 hole
1 Dialysis tubing, attached to glass nozzle,
with stopper seating and tubing clamp
2 Replacement dialysing tubing
Diffusivity is the ability of a substance to permeate
another medium even through porous
materials. This process is particularly noticeable
for gases, as the mobility of gas molecules is far
greater than the molecular motion of solids or
liquids; diffusion can, however, also take place in
solids and liquids.
In diffusion, all molecules in the observation
area eventually mix and the composition becomes
uniform; the time required for complete
mixing depends on the temperature and the
molecular density of gases concerned. Diffusion
is faster at higher temperatures and low molecular
densities than at lower temperatures and
high molecular densities.
In the area of biology diffusion is of great
importance to the exchange of gases in
breathing organs.
Osmosis apparatus with stand material