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How do I balance  Fe2(SO4)3 + KSCN  =  K3Fe(SCN)6 + K2SO4 ?

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bandmanjoe eNotes educator | Certified Educator

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This equation looks really, really hard, but if you follow these steps, it's not all that bad.  First, set up a grid that shows all the atoms that are used in this particular equation, with two sides, one to count for the reactants side, then one to count atoms for the products side.


Fe        2             1

SO4     3             1

K         1             5

SCN     1             6

You count the number of atoms for each atom (or group of atoms, in the case of SO4 and SCN) and list them.  The idea is to use coefficients, which are large numbers placed in front of the compound which act as multipliers, they multiply everything in that molecule.  The first thing I would do is put a "2" in front of K3Fe(SCN)6.  The 2 now gives me 2 Fe's on the product side (don't forget: it also multiplies times everything else in the molecule).  Go to the product side of your chart, and adjust the numbers, like this:


Fe        2           2

SO4     3           1

K         1           8

SCN     1           12

Now to the sulfate group; I would put a coefficient "3" in front of K2(SO4) to give me 3 sulfates on the product side.  Don't forget to go back and adjust the numbers on your chart, and don't forget, this also affects the K numbers.  It should look like this:


Fe        2           2

SO4     3           3

K         1           12

SCN     1           12

The next part is easy---I need 12 atoms each of K and SCN on the reactants side of the chart, so the easiest solution is to put a coefficient "12" in front of KSCN on the reactants side.  Go back to your chart and adjust the numbers, it should now look like this:


Fe       2           2

SO4    3           3

K        12         12

SCN    12         12

When the number of atoms on both the reactant side and product side equal, you have balanced the equation.  The final result looks like this:

Fe2(SO4)3 + 12KSCN ---> 2K3Fe(SCN)6 + 3K2(SO4)

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Jyotsana | Student

Fe2(SO4)3+12KSCN=> 2K3Fe(SCN)6+3K2(SO4)

When you balance both side has to equal.