Variables
The variables in this experiment could the metal that is used, the volume of copper sulphate used and different chemical amounts. In the experiment I will roughly use 0.01 moles of each metal
Mole= 6.02x10 to the power of 23
Mole=mass/atomic mass
Or
Moles x Atomic mass= mass
Magnesium-0.01x24=0.24g
Copper-0.01x12=0.64g
Lead-0.01x207=2.07g
Zinc-0.01x65=0.65g
Iron-0.01x56=0.56g
Fairtest
To ensure that the experiment will be carried out fairly I tend to ensure that each metal has been measured out correctly using scientific scales, test each metal at least 3 times to make sure that there are no anomalous results. Also to keep the experiment a fairtest the amount of copper sulphate solution should be kept the same, the amount of metal should also be kept the same but not the weight it must be measured in moles. To keep the test fairer still the temperature must be kept the same of the copper sulphate solution as a slight increase in the temperature of the copper sulphate would make the reactions take pace more quickly and make the results unfair.
Apparatus
The apparatus I will be using include:
- The 5 metals: Iron, Copper, Magnesium, Lead and Zinc.
- Test tubes
- Test tube racks
- Copper sulphate 10cm3
- Thermometer
- Stopwatch
- Measuring cylinder
Method
Our brief was to determine the reactivity of 5 metals, using copper sulphate solution to determine which one was more reactive by reacting each metal in turn with this solution we will do this by measuring the energy change. After we had determined the reactivity of them we had to put them in a reactivity scale. To carry out this experiment you will need to follow these steps:
Collect all the necessary apparatus for this experiment these included the 5 metals, 12 test tubes, 2 test tube racks, 10cm3 of copper sulphate solution, thermometer and a stopwatch. Measure each metals weight in moles so that they all have the same amount of atoms in each metal. Magnesium must be weighed to 0.24g, Copper to 0.64g, Lead to 2.07g, Zinc to 0.65g and Iron to 0.56g. Measure out 10cm3 of copper sulphate solution and place into a test tube after this record the temperature of the copper sulphate solution and record onto your results table. Then place the metal that you are testing into a test tube filled with 10cm3 of copper sulphate solution. Record the end temperature of the reaction (the highest temperature that the reaction reaches) and mark this onto your table. Repeat for all metals except for copper sulphate, as there will be no reaction as there is nothing to displace.
Hypothesis
I believe the metals would react in the following order of reactivity
I believe this because my preliminary experiment on displacement reactions gave me these results even though the solutions used are different they still give me an indication of which order the metals may react in. The preliminary experiment showed me that magnesium displaced every solution it was placed in except for its own. This is due to the amount of electrons that magnesium has on its outer shell and how close the outer shell is to the nucleus of the element. The ease at which elements are willing to give up there spare electrons to gain a full outer shell is an indication of how reactive that particular element is, also the ease or difficulty at which the element is extracted is another indication of how reactive an element is for example: Magnesium is hard to extract where as gold can be found in its natural state without anything having to be done to it to extract it.
Analysis
This is the results table for the experiment. As you can see from the table that magnesium was the most reactive and displaced the copper thus meaning that copper was the least reactive as it displaced nothing as there was nothing for it to displace apart from itself which it cannot do. To represent this information on the table I will be displaying it on an “Average temperature change” graph.
I can also represent this information on an energy exchange graph the following is the equation that is used to find it out.
Q=MC∆T
OR
Energy exchange= Mass of copper sulphate X specific heat capacity X change in temp 0c
AND
J= 10g X [4.2/g/0c]
Lead -10 X 4.2 X 1.7= 71.4j
Iron - 10 X 4.2 X 5.7= 239.4j
Zinc -10 X 4.2 X 10.7= 449.4j
Copper - 10 X 4.2 X 0.4= 16.8j
Magnesium - 10 X 4.2 X 42.3= 1776.6j
Conclusion
By looking at my results and my energy change diagram I have come to the conclusion that my prediction was correct and the metals did react in the order that I predicted them to:
In my energy change diagram it showed me that the higher the energy exchange the more reacting that was taking place, thus meaning that the higher the energy exchange the more reactive the metal was, the metals reacted in this way because of the amount of electrons they have on their outer shell this has to o with the ease at which they are willing to loose the extra electron they have for example; magnesium has an extra one electron and is willing to give that up easily so that it can gain a full outer shell as it is easier for an element to loose one electron than gain 7. It also depends on how close the outer shell is to the nucleus of the particular metal.
Evaluation
Experiment faults: The main things that could have affected the experiment could be contamination of the test tubes if they had not been cleaned properly and could have other metals inside them this would of interfered with the results. The temperature at which the copper sulphate solution was, for example; while the experiment was being carried out we ran out of copper sulphate so the technicians had to make some more, the copper sulphate solution that replaced the other one could have been made up of different amounts of copper and also the temperature changed because it had only jus been made. Another experiment fault could have been if the solution were accidentally mixed this would have affected the rate of reaction. If different scales were used when weighing the metals this could affect the experiment as they could be of different sensitivities.
Experimental error: I believe that I did not perform big experimental errors as our results followed my prediction and my preliminary experiments results. The error I believed that I carried out was: the accidental stirring of the metal in the solution of copper sulphate.
