Results
Calculations
1. Amount of Hydrogen = volume/molar volume
0.0228dm3 / 24dm3/mol
= 0.00095mol of hydrogen
2. M (s) + 2HCl (aq) MCl2 (aq) + H2 (g)
3. 1 mol of M 1 mol of H2
Therefore 0.00095 mol of M 0.00095 mol of H2
Therefore Molar Mass = mass/amount
= 0.033g / 0.00095
= 34.74 g/mol
The rest of the results were as following;
Repeats
These atomic masses show us that the metal X could be any of the following:
Selenium, Bromine or Strontium.
As some of these elements are not actually metals, I don’t think that it is possible that metal X could be one of these. These results are very surprising indeed as I thought the metal was magnesium. I still think it is though and I think I must have made some errors while carrying out the experiment or making my calculations. It is strange though that all my results were anomalous.
Evaluation and Conclusion
In this experiment I think that there were many errors, otherwise my results may not be so strange. Even though I have no evidence that Metal X was magnesium, I do believe it to be and magnesium has an atomic mass of 24.3. My results show very different patterns and they are far too different for me to call them reliable. I thin that the quality of my results is very poor indeed. As for anomalies, I think that all my results are anomalies, but I don’t know how this came about. There are certain errors within the experiment that may partially account for the unreliable results. But I will talk about that in the errors section. There are certain changes that I would make to this experiment. Firstly I would use a gas syringe to increase the accuracy of the readings. I would also try and do something to stop the gas escaping before the bung was securely fixed. This may have been something to do with the errors. I have come up with a suitable solution for this:
Also I think that the rubber stoppers were not entirely fixed well. I think that some gas may have been able to escape. For this error I think that I would use ground-glass stoppers. I would also use a burette instead of a measuring cylinder so that I was more accurate when measuring HCl. Again in a better experiment you might want to get rid of the oxide layer on the magnesium before weighing as this may take up some mass.
Errors
This experiment has many errors and I some of these may be able to account for my anomalous results. Firstly some gas may be given off before I have had the time to place the cork in the flask. This would mean that I lose some volume of gas. Also the magnesium may have been impure and the oxide layer may have taken some of the mass. I also found that when I was trying to weigh my magnesium the balance was wandering and I had to pick a reading and this may not have been the most accurate. Also when the bung is pushed into the flask it may displace some air and create an error.
Further Work
If I was going to do further work I might use some different metals. I might also use different acid concentrations and different acids altogether. Also I might like to find the relative atomic mass of a metal using a more accurate method and achieve mor3e accurate results. I would use the method of some kind of electrolysis.
