What mass of potassium dichromate is required to oxidize an #100*mL# volume of #Fe^(2+)# solution whose concentration is #0.10*mol*L^-1#?

1 Answer
Feb 17, 2017

Answer:

#"Approx. 1/2 a gram of potassium dichromate............"#

Explanation:

We need an oxidation equation:

#Fe^(2+) rarr Fe^(3+) + e^-#

And a reduction equation:

#Cr_2O_7^(2-) +14H^(+) + 6e^(-) rarr 2Cr^(3+) + 7H_2O(l)#

Overall:

#Cr_2O_7^(2-) + 6Fe^(2+) + 14H^(+)rarr 2Cr^(3+) + 6Fe^(3+) +7H_2O(l)#

#"Moles of"# #Fe^(2+):#

#100xx10^-3*Lxx0.10*mol*L^-1=0.010*mol#

And thus we need #(0.010*mol)/6xx294.18*g*mol^-1=0.490*g# #K_2Cr_2O_7#.