An investigation of the percentage of oxygen in air.

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Datacollection:
Since we failed in many stages of our investigation, there was no data to collect.

Conclusions: Even though the results of our experiment were absent, the description of our task revealed what was going to happen. It is to read that the copper wire will turn black as it forms copper oxide and that there will be a change in air volume. I expect the the airvolume to be less than before. That is because the copperoxide, witch demonstrably has covered the copperwire (the wire becomes black), will make the oxygen take less place than if it would be a gas. By dividing the amount of volume that has disappeared with the volume to start with an approximation of the percentage of oxygen in the air can be made. The approximation of the air volume that is to start with must be taking in account the air present in the rubber hoses and the glass tube.

The oxygen in copperoxide will be bound tightly to the copper, tighter than when it was in gas state. The copperoxide will remain on the copper wire, something that is clearly visible. What else could the colour change of the wire depend on? So, that is why I think that the air volume will decrease. Of course, the oxidation of the copper is started because of the heat which is the energy that is needed to start the reaction.

Evaluation: The fact that our experiment failed, and the many ways in which how we failed can be used to show the weaknesses and risks of failures in the experiment. The first bad thing that happened was that our glass tube melted, partly because the heat was too high but also because it was hard to seize how far from the flame the tube should be held. An improvement would be to use a tube less easily melted. The other misfortunate thing that disturbed our investigation was that one of our rubber hoses left its hold of the syringe. This would not have happened if we had checked the apparatus more carefully. But it would have been easier to avoid if the hoses had been less fractured. We also drew the conclusion that if the apparatus had contained fewer parts the risks of failure had disappeared. The simplest solution is often the best one.

Discussions:
• Copperwire is more suitable than lump because wire conducts heat better than lumps, it fastens the reaction.
• The apparatus must be airtight if we shall be able to trust our data about the volume. With air gasps, that volume can be changed. There could also be oxygen left in the air.
• The syringes should be pushed back and forth so that the volume change will be measurable.
• The apparatus must be cool because hot gases have got bigger volumes than cool ones. If the measurements are to be correct the circumstances need to be the same.
• The gases left in the sy...