How many grams of Fe needed?

1. Sep 16, 2009

hils0005

1. The problem statement, all variables and given/known data[/b]

Given:
C2CL4 + Fe $$\rightarrow$$ C2H4 + CL- + Fe2+

A reservoir contains 5million gallons of water which is contaminated with 4.2mg/L of Perchloroethene(C2CL4). You want too reduce it to harmless ethene(C2H4) by reacting it with Fe. because of this only about 20g of the added Fe is reactive. If you need to treat 5million gallons of water, how many grams of Fe will you need to treat the Perchloroethene(PCE)?

2. Relevant equations

I first balanced the equation
C2CL4 + 4H+ + 4Fe $$\rightarrow$$ C2H4 + 4CL- + 4Fe^2+

Concentration of PCE=4.2mg/L
5mill gallons of water = 1.89 x 10^7 L

I do not know where to go from here

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 16, 2009

symbolipoint

How many times bigger is the amount of PCE in the 5 million gallon tank than in the elementary reaction? How many milligrams, and therefore moles, of PCE is in the tank? I believe some information is missing related to your "20 grams" comment about the Fe.