1) The copper-zinc cell has and EMF of 1.100V at standard conditions. What is th
ID: 865262 • Letter: 1
Question
1) The copper-zinc cell has and EMF of 1.100V at standard conditions. What is the EMF when the concentration of Zn2+ on the anode side is 0.05000 M and the concentration of Cu2+ on the cathode side is 3.000 M? The units are volts and use at least 4 significant digits in the answer. The error interval is 0.02 V.
2) How long (in hours) will it take to create 45.1 grams of pure copper from a copper(II) solution with a 5.00 W power supply operating at 4.00 volts? Assume all the energy is used to reduce the copper ions and none is lost by hydrolysis of the solution. The units are hours.
Thank you
Explanation / Answer
1) Since -
E(cell) = E0(cell) - (0.0592/n) log Q
Where, for the reaction - Zn (s) + Cu+2 (aq) ---------> Cu (s) + Zn2+ (aq)
From the given concentrations - Q = [Zn2+] / [Cu2+] = 0.05 / 3.0 = 0.016 mol/L
Hence - E(cell) = 1.10 - (0.0592/2) log (0.016) = 1.153 V
---------------------
2) From the given data -
Current passed through the solution = 5.00 W / 4.00 V = 1.25 C/s
Therefore -
Mass = (e)(c)(time)
time = mass / (e) (C) , where , e = electrochemical equivalent = 63.55/2*96500 = 3.29*10-4
= (45.1 g) / (3.29*10-4 )(1.25 C/s) = 109574.19 sec = 30.43 hrs
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.