GChem Achiever Question. helpp

[anonymuz]

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What percent of iron is present in the ore if a 1.120g sample requires 25ml of .050M KMnO4 to fully oxidize all of the dissoved Fe2+?

8H+ + 5Fe2+ + MnO4- -> 5Fe3+ + Mn2+ + 4H2O

Answer is:
5 * (25/1000) * .050 * 55.85 * (1/1.120) * 100%

i understand everything but the last 2 multiplications.... (1/1.120) * 100%

Thanks

 

[UndergradGuy7]

5 * (25/1000) * .050 * 55.85 gives you the grams of Fe2+.

The questions asks what percent of iron is present in the ore if a 1.120g.
So (Fe2+ / 1.120 g) * 100

So the last part makes percent of Fe2+ in the total sample.

 

[anonymuz]

oooo got it! thanks a lot the 1 in the numerator was throwing me off didnt realize i just takes grams of Fe2+ / 1.120. thanks!