chemistry - Dr.Bob222 please help

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 the 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?

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 the 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?

For #1.
I would try this. The problem states, implicitly at least, that copper is the limiting reagent (otherwise, there would be no Zn coating left on the galvanized iron nail at the end of the experiment). Therefore, you will have used 1.00 L x 0.0701 M = 0.0701 mols Cu^+2. Since the reaction is
Zn + Cu^+2 ==> Zn^+2 + Cu, there is a 1:1 ratio, and you must have used up 0.0701 mols Zn that came from the galvanized iron nail. Mols should convert into grams. You will need to calculate the grams Zn at the beginning, subtract the grams Zn used in the reaction to arrive at grams Zn remaining, convert that to thickness at the end knowing the original thickness was 1/32". I think you will need to work in volume in order to obtain final thickness but there may be other ways to get at it. This should get you started.

I'll think about #2 but don't hold your breath. I've done these BUT the procedure I use is different than is being taught today and I don't know if I can convert to the present standards or not. However, the reduction half reactions you need are as follows:
Br2 + 2e ==> 2Br^-
Fe^+3 +e ==> Fe^+2
I presume the ferrous ion is being oxidized to ferric ion and the bromine is being reduced to bromide ion. Note that the iron equation must be multiplied by 2 before adding to the bromine equation to obtain the full reaction. That is, the reaction, as it occurs spontaneouslyhalf as an oxidation and half as a reduction) is
2Fe^+2 + Br2 ==> 2Fe^+3 + 2Br^-

If the equation is all that's holding you up that should take care of it. I hope this helps.

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