[samuraix]

 Can somebody help me with the calculation? If possible , please provide full calculation so that i understand better.
  
 
1. We have 100mL of a solution of Cu2+ ion and wish to determine the concentration of the solution.We electrolyze the solution to produce solid Cu and use 1.5 A of current for 1120 seconds to complete the process. What was the concentration of Cu2+ in the solution?
 
2. The reaction occuring in the cell in which Al2O3 and aluminum salts are electrolyzed is :
                                        Al3+ (aq)  + 3e  become   Al (s)
If the cell operates at 5.0 V and 1.0x105 A , and you want to produce 2.7x 105g of aluminum , how many hours will you need to operate the cell?
 
3.In reducing Ag+ ion for plating onto jewelry , an operating cell voltage of 4.0V is required . If you run a business that does this kind of work , how much will the elctrical  energy cost to coat 1.0x104 necklaces with 0.10g silver each?Assume that the cost of electricity is RM 0.10/kwh.(Given: 1J=1C.V ; 1kwh=3.6x106J)

It is not that i did no attempt to try but our lab instructor syllabus is not the same we learn in class. The lab sllabus is way ahead  of us. Even if i read the text book , i still can't understand the caluclation part. I am weak especially come to calculation part. This will be my last post because this is the last experiment. So hope you all can help me with it.

[Sev]

1. The number of coulombs of e-s transferred can be calculated using q = It (I is current, t is time).

Use Faraday's constant to calculate the moles of e-s (n = q/F).

This amount of e-s is used to reduce Cu2+:  Cu2+ +2e - Cu(s). 
Use mole ratios to find the moles of Cu2+ in solution.  Working out the molarity is straight foward from here.