Hypothesis: it is hypothesised that the heavier metals with greater density and volume will be more likely to be metals like lead and the metals with small mass, density and volume are more likely to be metals such as tin and aluminium.
Type of variable
Cu, PB, Fe, Al, Zn, Sn
Volume of metal and mass of metal
Volume of metal was determined by displacement of water. The mass will also be determined. Density will be calculated
All metals will be kept at 25 degrees centigrade
Physical shape of metal
All metals folded out straight to keep air bubbles from distorting the displacement.
N.B original volume of water was considered but was decided that it would not have any affect on volume.
The metals all sat in the water and did not float. None off them reacted with the water and gave off bubbles. The heavier metals also felt heavier in the hand were also larger in physical size. The lighter metals were smaller in physical and mass size.
The data obtained from this experiment has been manipulated in this way to show the density. The data has been put through the formula density=mass/volume. This will determine the density which then can be graphed.
The calculation made from the raw data was that initial volume was taken away from final volume. This first then gave volume of the metals which then could be out into the formula density=mass/volume. Therefore density=26.8/3. This gave the density which then could be graphed. The r2 in the graph is the density. The error for the density was calculated by finding the percentage error of volume and mass and then adding them together. This created quite a large error as the percentage error was as big as the reading is some cases.
Unknown Metal Mass, Volume and Density
This graph had such large areas due to equipment being very inaccurate. The data collected had errors almost as large as the reading itself thus making the percentage error very large.
The metals had a large range of density’s which was partly due to inaccurate equipment making very large errors.
This graph directly above shows the percentage error against the reading. As can be seen the percentage error is very large due to when measuring the volume the error + 0.5 was as large as the volume of the metal itself.
Conclusion and Evaluation
These density somewhat support the hypothesis that the heavier metals are lead and the lighter ones aluminium. The readings taken were too inaccurate to justify each metal. Each density at least had an error of + 15% but in some cases reached + >50%. This was due to highly inaccurate measuring equipment especially the measuring cylinder. It is to hard to tell which metal is which with the readings taken and calculated due to the large errors in them.
Limitations of experimental design
The experimental design definitely did not help answer the question as there were to many errors to determine which metal was which. There were a few limitations to the design of this experiment. They were:-
Inaccuracy of equipment (especially the measuring cylinder)
Metals be unnamed (a,b,c, etc) so that they could have been mixed up
The main and foremost error in this experiment was definitely the equipment as it was so inaccurate that it gave errors as large as the reading itself. Both of these systematic errors made it harder to provide proper data to be manipulated into the right density for each metal.
Suggestions for Improvement
To improve this experiment it is suggested that higher accuracy equipment is provided as this will give smaller errors and so the overall percentage error