A student constructs a Zn|Zn^2+(1.0 M) || Cu^2+(1.0 M)|Cu galvanic cell with a KNO3 salt bridge and reads the voltage with a high-impedance voltmeter. Standard reduction potentials: Cu^2+/Cu = +0.34 V; Zn^2+/Zn = -0.76 V. The measured cell voltage at 25 C is 1.08 V.
What is the standard cell potential E_cell^o, and how does the measurement compare?
- A
E^o = +1.10 V; measured value should be exactly 1.10 V
- B
E^o = -1.10 V; cell is non-spontaneous
- C
E^o = +0.42 V; measurement is too high
- Dcheck_circle
E^o = +1.10 V; measured (1.08 V) is slightly low, consistent with internal resistance / non-ideal conditions
Explanation
E^o_cell = E^o_cath - E^o_an = 0.34 - (-0.76) = +1.10 V. Measured 1.08 V is within typical experimental error.