Home › AP Intermediate 2nd Year › Chemistry › Electrochemistry › Given standard reduction potentials $E^{\circ}(\…
Given standard reduction potentials $E^{\circ}(\mathrm{Cu^{2+}/Cu}) = +0.34$ V and $E^{\circ}(\mathrm{Zn^{2+}/Zn}) = -0.76$ V, the standard EMF of the Daniell cell is:
A$+0.34$ V
B$+1.10$ V
C$+0.42$ V
D$-1.10$ V
Answer & Solution
Correct answer: B. $+1.10$ V
Cu is the cathode (higher reduction potential), Zn is the anode.
$E^{\circ}_{\text{cell}} = E^{\circ}_{\text{cathode}} - E^{\circ}_{\text{anode}} = (+0.34) - (-0.76) = +1.10$ V.
The positive value confirms the reaction is spontaneous as written. A common slip is to drop the negative sign on Zn, giving $+0.42$ V — option A is the trap.
Related questions
For an electrochemical cell operating spontaneously, ΔG° is related to E°_cell byWhich of the following statements about electrode potentials is INCORRECT?The overall cell reaction of the lead storage battery on discharge isThe primary cell that cannot be reused after its EMF drops to zero is exemplified byRusting of iron requires which two chemicals in contact with the metal?Fuel cells directly convertThe specific conductivity of a 0.1 M KCl solution is 1.29 × 10⁻² S/cm. The molar conductivMolar conductivity of a strong electrolyte at concentration c is related to its limiting v