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## Homework Statement

A percent yield lab says to add 5.00 g of CuCl

_{2}•2H2O(s) to 50 mL of dissolved water. Then, add 1.0 g of steel wool (100% iron) to the beaker.

I am trying to find out how many moles of CuCl

_{2}react here. I am confused about the dihydrate.

## Homework Equations

The reaction given in the lab is

Fe(s) + CuCl

_{2}(aq) → FeCl

_{2}(aq) + Cu(s)

## The Attempt at a Solution

To find out how many moles of CuCl

_{2}•2H

_{2}O(s) I used, do I calcuate the molar mass including the dihydrate? Or do I use just the molar mass of CuCl

_{2}?

I think I am supposed to include the dihydrate in the molar mass calculation, but I'm confused because the dihydrate doesn't appear in the reaction. It doesn't react with anything. So wouldn't I need to figure out how many moles of CuCl

_{2}there were, not how many moles of CuCl

_{2}•2H

_{2}O(s)?

Also, I know the CuCl

_{2}•2H

_{2}O(s) is the excess reactant, but to show that, I need to find out how many moles of it I have first.