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The chemistry of corrosion is quite complex but it can be understood by considering it as an electrochemical phenomenon. Consider a particular spot on an object where corrosion takes place. At here oxidation takes place and this spot behaves as the anode. The released electrons at anodic spot go through the metal and go to another spot on the metal and reduction of oxygen takes place in the...
The two materials are methane and methanol that can be used as fuels in fuel cells.
The lead storage battery can be recharged by reversing the direction of current passing through it.  For recharging PbSO4 is converted into Pb at the anode and into PbO2 at the cathode. The chemical reactions are as follows:-              
It is clear from the given reaction that reduction of 1 mol of Cr2O72- will be                                                                       =   6 F                                                            (as 6 electrons are required to balance the reaction;  Charge required = nF)                                                                                                         ...
Metals like Na, Mg, Al, etc. are produced on a large scale by electrochemical reduction of their respective cations or by the process electrolysis because there are no suitable reducing agents available for this purpose.
Firstly we will find total charge flown through the wire then we will calculate number of electrons. We are given :-         I = 0.5 A,    Time = 2 hours = 7200 seconds. We have,                  Q = I.t                                     = (0.5)7200 = 3600 C. Now we will convert charge into number of electrons. We know that                      So toal number of electrons :                  ...
We know that :-                                                                                                For degree of dissociation, we have :-                                                             or                                                             For dissociation constant, we have :-                                               or                                     ...
We know :                                                                     If we draw a straight line between  and , its slope will be -A and the intercept on the y-axis will be . In this way, we can obtain the value of limiting molar conductivity.
The conductivity of a solution depends upon the number of ions and the distance between them. In the process of dilution, we don't increase the number of ions in the solution instead we increase the distance between them. So the conductivity of the solution decreases due to dilution.
For finding Gibbs free energy we know the relation :-                                                                                                                                                                                                                          Now, for equilibrium constant we will use :-                                             So,                                 ...
Here we can directly apply the nernst equation :-                                        Putting the value in this equation :-                                          or                                    or                                     Hence the required potential is 0.914 V.
It is given that pH of the solution is 10,i.e.,  the hydrogen ion concentration in the solution is 10-10 M.                                                        By Nernst equation we have :-                                                  So,                                                       or                                                          So the required potential is - 0.591 V.
The oxidising strength of elements increases as the standard electrode potential increases. So all the elements having greater standard potential than iron can oxidise it to a higher state. Few such elements are :-   F2,  Cl2,  Br2,   Ag+1  etc.
The standard electrode potential of Zinc is - 0.76 whereas that of Copper is 0.34. So Zinc will reduce copper into the lower state. It is known that zinc is more reactive than copper. Thus if we will store copper sulphate solution in zinc pot then zinc will displace copper from its solution. The following reaction will take place:-                              
To determine the standard electrode potential of the given system we need to use a hydrogen electrode. In the setup, we shall put a hydrogen electrode as cathode and Mg | MgSO4 as an anode.                                          Now we will measure the emf of the cell. This emf will be the standard electrode potential of the magnesium electrode. E°cell = E° right  – E°left E°left =0 ( The...