1. Calculate the pH of the cathode compartment solution if the cell emf at 298 K
ID: 877821 • Letter: 1
Question
1. Calculate the pH of the cathode compartment solution if the cell emf at 298 K is measured to be 0.620 V when [Zn2+]= 0.23 M and PH2= 0.94 atm .
2. One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell, ________.
O2 gas is produced at the cathode
a nonspontaneous reaction is forced to occur
oxidation occurs at the cathode
electrons flow toward the anode
an electric current is produced by a chemical reaction
A voltaic cell utilizes the following reaction Al(s) +3Ag ()Al()+3Ag(s) What effect does each of the described changes have on the cell emf? Drag the appropriate items to their respective bins. HCl is added to the AgNO3 solution, precipitating some of the The size of the aluminum electrode is Water is added to the anode compartment, diluting the solution increased Ag+ as AgC A solution of AgNO3 is added to the cathode compartment, increasing the quantity of Ag but not changing its concentration. Cell emf will increase Cell emf will decrease Cell emf will remain the sameExplanation / Answer
The solution is as follows.
1. First we should find the reaction quotient for the reaction.
Products are Zn²+ and H2 gas and reactants are H+ ions and Zn metal,
Zn metal being solid and pure, its concentration will be a constant and will be included in the constant
Q = [Zn²+][PH2] / [H+]²
(PH2 is pressure of H2 gas and has nothing to do with pH, also, H+ has an exponent of 2 because it has 2 as its Stoichiometric coeffecient)
Applying Nernst equation,
E = E - (0.059/n) log Q
0.62 = (0.76 - 0) - (0.059/2) log ( [Zn²+][PH2] / [H+]²)
0.62 = (0.76 - 0) - (0.059/2) log [ (0.23)(0.94) / [H+]² ]
Solving this equation,
[H+] comes out to be = 1.97 x 10^-3 M
pH = - log [H+] = - log (0.0029) = 2.7
Thus, pH is found to be 2.7
2. One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell, a nonspontaneous reaction is forced to occur.
3. Not clear
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