[ajones51]

Hi Everyone,
Anyone want to try giving these a shot?

The right electrode in a cell is a piece of copper immersed in a 1.00 L solution of 0.0701 F copper sulfate. The left electrode is a galvanized nail (i.e., an iron nail that is completely coated with a layer of zinc), immersed in a solution containing 1.00 L 0.0224 F zinc sulfate.
As the reaction proceeds, the zinc coating of the nail will gradually get thinner and thinner as zinc is consumed in the reaction. Assume that the iron nail (excluding the zinc coating) was 1/8" in diameter, and that the zinc coating for the nail was 1/32" thick. What is the thickness of the zinc coating that remains once the reaction goes to completion? Provide your answer in centimeters to 3 sig. figs. (don't enter units). You will need to know that the nail was immersed in the zinc solution to a depth of 10.5 cm.

I have found the Area of hte Nail and the Area of the zinc and subtracted the two to find the area difference.  I then tried to figure out which one is limiting.  I am stuck in trying to convert from area into concentrations.  I realize I need to use the density of zinc to do this, but can someone please help walk me through it or anything?

Q2: A cell consisting of a Pt indicator electrode and an SCE reference electrode is used to follow the titration of 40.00 mL of a 0.0200 F Br2 (the unknown) with 0.0200 F Fe2+, each in the presence of 1 mol/L HCl (the titrant). Calculate the voltage of the cell following the addition of 60.0 mL of the titrant to the unknown.

I found hte moles of iron that I have and tried to write an overall reaction between Fe and Bromine but I am having trouble doing that.  Can anyone help walk me through that? 

[Borek]

I have found the Area of hte Nail and the Area of the zinc and subtracted the two to find the area difference.  I then tried to figure out which one is limiting.  I am stuck in trying to convert from area into concentrations.  I realize I need to use the density of zinc to do this, but can someone please help walk me through it or anything?

Area is not what you need, volume of zinc is. You are right you will need zinc density, probably wikipedia will give you an instant anwer. To find out volume of zinc go for hollow cylinder - ie. calculate initial volume of coated nail and final volume of coated nail, then substract the two.

I found hte moles of iron that I have and tried to write an overall reaction between Fe and Bromine but I am having trouble doing that.  Can anyone help walk me through that? 

Which one gets oxidized (and to what)? Which one gets reduced (and to what)? Once you will answer these writing the reaction is a breeze. Calculate stoichiometry to find out final concentration of the excess reactant, then use Nernst equation. You will need table of standard potentials for that.