4. Wait a few minutes and you will see how the reaction starts to take place, until a reddish layer forms on the aluminium sheet, which corresponds to the copper formed in the reaction. In the following section you can see the reactions and equations that take place until you get to the copper.
<\/li>\n<\/ul>\n <\/p>\n
TECHNICAL EXPLANATION OF THE EXPERIMENT<\/h2>\n
Let's look at the redox equations of the reaction. To do this we first look at the oxidation potentials of the components:<\/p>\n
Al3+(aq) + 3e- \u2192 Al(s) +1.676V
\nSO42-(aq) + 4H+(aq) + 2e- \u2192 2H2O(l) + SO2(g) -0.17V
\nCu2+(aq) + 2e- \u2192 Cu(s) - 0.340V<\/p>\n
We see that the materials with the greatest potential to enter into oxidation-reduction would be Aluminium (which is oxidised) and Copper (which is reduced). On the other hand, the reaction will take place in an aqueous solution of copper sulphate, which would be sufficient to conduct the electrons to be transferred. To increase the conductivity of the solution we are going to add sodium chloride (common salt), in this way our reaction will be accelerated and we will be able to see the effects more quickly.<\/p>\n
The reaction that will therefore take place is:<\/p>\n
CuSO4 + Al -> Al2(SO4)3 + Cu<\/strong><\/p>\nAs soon as the aluminium metal is introduced into the copper sulphate solution, a reddish layer starts to form on the aluminium in a few minutes, this is already the reduced copper (copper metal) that is being deposited on the aluminium. If we maintain the reaction over time, the copper will continue to deposit until all the copper in the solution is consumed (or until all the aluminium is consumed, which in this case would not be the case because there is more aluminium than copper sulphate).<\/p>\n