Copper Sulphate can be toxic and should not be swallowed. Although the
variable resistor will eliminate the danger of shorting, care should
still be taken when working with electricity and liquids, avoid
contact between the two elements. Ineffective electroplating can
produce a finely divided solid of copper, avoid contact between this
and the eyes, and also avoid digesting it. Hands should be washed
thoroughly after each experiment. The usage of safety glasses is
necessary in case of violent reactions occurring and electrical
devices are in operation. The usage of aprons is required as chemicals
may be spoil or stain the clothes of the chemists. Gloves should be
also used due to the usage of chemicals so they do not cause damage to
the skin.
The ammeter is also a safety precaution to ensure that the current was
not too high, and the current should be controlled and kept at
constant level of decrease or increase. Electric equipment should be
handled with dry hands so that electrocution does not occur. It is
essential to set up the circuit properly, especially to set up the
ammeter; we have to make sure that the positive of the ammeter
connects to the positive of the circuit. And the negative of the
ammeter connect to the negative of the circuit.
ANALYSIS
From the experiment and by looking at the graph I have presented, it
can be worked put that the amount of change in mass is directly
proportional to the change in current. It is meaning that the amount
of mass lost and gained during the experiment of electrolysis depended
on the amount of charge that is put in so the more you put in the
greater the amount of mass lost and gain.
From the graph when the best-fit line is drawn I can see that they do
line up but for the cathode graph it is not as perfect though. This is
because of some errors had occurred during the experiment. Comparing
to the actual amount of mass lost I am not very far off. The method
and the equation I have mentioned early on in background knowledge can
calculate the actual mass change.
The prediction I have predicted has come out to be exactly the same as
the experiments, which is that the change in mass will be proportional
to the change in current. The graph of the results of the experiment
when compare with the one of the actual mass it looks quite the same
but some are anomalous, the anomalous results were circled in the
graph to distinguish from the other values.
CONCLUSION
Due to my results, it shows that during the process the anode loses
mass because the copper atoms lose electrons and become copper ions,
Cu2+ (aq).
Copper atoms à copper ions + electrons
Cu(s) Cu2+ (aq) 2e-
The electrons released at the anode travel around the external circuit
to the cathode. There the electrons are passed on to the copper ions,
Cu2+ (aq), from the copper II sulphate solution and the copper is
deposited or copper plates on to the cathode.
Copper ions + electrons à copper atoms
Cu2+ (aq) + 2e- à Cu(s)
According to my results it showed that when the current increases, the
mass gained on the cathode also increased. They are directly
proportional to each other. The mass gained is directly proportional
to the current in the circuit. It is because when the current is 1A,
there is one unit of electrons that have been discharged, and become
copper cation. These ions have been attracted by the cathode, at the
same time, the gained electrons from the cathode, and become copper
atoms again and deposited on the cathodes.
Cu2+ (aq) + 2e- à Cu(s)
1 mole 2 moles 1 mole
We require 2 moles of electrons to produce 1 mole of copper atoms from
1 mole of copper cations. Also an increase in current means that there
is more resistance which occurs in the solution. This gives out heat,
which is an exothermic reaction. This meaning that there will be more
collisions and more ions with enough activation energy to carry out a
successful collision. Therefore the rate is increased.
EVALUATION
I am very pleased about the results that I have obtained. They are
accurate, and they can enable me to prove that the theories in my
predictions are correct. There are several points that I think I have
done quite well to obtain these results. The method, which was used,
was reasonably good and the correct apparatus was used well also. It
was very simple to set up and carry out, using the method which was
chosen. It was simple and safe procedure. But there was room for
improvement.
Using the purest copper available could also make the results more
accurate. By using a digital ammeter to secure a much more accurate
reading on the current flow. Using the digital rheostat, to keep the
current the same, the sliding rheostat is much harder to use as moving
it to try and establish a constant current flow was very hard. Using
the current rheostat, the current readings were fluctuating and were
complex to maintain its stability. The copper II sul