The standard EMF of a Zn|Zn²⁺||Cu²⁺|Cu cell (E°_Cu²⁺/Cu = +0.34 V; E°_Zn²⁺/Zn = −0.76 V) is
- +1.10 V
- +0.42 V
- −1.10 V
- −0.42 V
Show answer and solution
Correct answer: A. +1.10 V
1. Daniell cell: Zn (anode, oxidation), Cu (cathode, reduction).
2. E°_cell = E°_cathode − E°_anode = 0.34 − (−0.76) V.
3. E°_cell = 0.34 + 0.76 = +1.10 V.
4. Positive value means the reaction is spontaneous as written.
_Source: syllabus Chemistry, Unit 3 "Electrochemistry", §3.2_