Microscale Chemistry Experimentation for Teachers
Volumetric measurements in a syringe during rusting:
Volumetric measurements in a syringe during rusting:
Left:
A piece of wetted steel wool is fixed inside the upper part of a 1-ml-syringe.
The
volume of 1ml air is closed by dipping the syringe into coloured water.
The
right vial contains dry steel woolI above 1ml of air which is also closed
by dipping into coloured water.
Obervations
after half a day: In the syringe with wetted steel wool 20 of 100 units
(0.2 ml of 1.0 ml) air are replaced by coloured water. There is no further
decrease of air volume in the following days.
The
air volume in the syringe with dry steel wool shows nearly no decrease.
Right:
The wetted steel wool shows some rust.
Explanation:
0.2 ml oxygen contained in 1.0 ml of water were bonded by iron during rusting.
Water
is needed for the rusting process: Dry steel wool did not consume air.