Introduction
During the rusting of iron, oxygen from the air reacts with it to form iron oxide and, at the same time this iron oxide combines with water to form hydrated iron oxide. In this experiment the use of oxygen in this process can be seen in that, in a sealed container, the level of oxygen reduces with time.
Equipment required
- PC with PicoLog datalogging software installed
- DrDAQ Data Logger
- Oxygen in air sensor (DD103)
- 1 litre beaker
- Beehive shelf
- Trough — ice–cream container
- Water
- 5 g steel wool — fine mesh to provide a large surface area
- Sticky fixers
Experiment setup
The experiment should be set up as shown in Figure 1.
Connect the DrDAQ datalogger to the parallel port (or USB if you are using a USB to Parallel port adaptor).
Mount the oxygen sensor, pointing upwards, on the beehive shelf. A little BluTack is useful for anchoring it in place securely. Run its connecting lead through the central hole of the beehive shelf.
Fill the trough with water at room temperature to a depth of about 3 cm and place the beehive shelf with the sensor into it. Plug the connecting lead into External socket 1 on DrDAQ.
Secure three ‘sticky fixers’ to the inside of the 1 litre beaker, above what will be the level of the water, and fix the steel wool to these. Now place this beaker, upside-down, over the beehive shelf and into the water so that it seals in the air.
Once the equipment has been set up, place it in a centrally heated laboratory or room so that the equipment remains at a near constant temperature.
Figure 1 The equipment setup
Carrying out the experiment
- Load PicoLog and configure it to collect readings of the oxygen sensor every minute for a whole day (1440 samples).
- Set it to start recording. When datalogging is complete, display the graph of percentage (%) oxygen against time.
Download the PicoLog settings
Further study
An extension to the experiment could be to place the trough, beehive shelf, oxygen sensor, beaker, steel wool etc. into a thermostatically controlled heated water bath, or on a hotplate, and see if temperature affects the rate of rusting and so the speed of uptake of oxygen. Temperatures up to 40ºC are OK. You could also see the effect of cooling, but do not go below 5 ºC as the operating range of the oxygen sensor is 5 ºC to 40 ºC.
