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Ferrochrome is an alloy of iron and chromium. Ferrochrome can be dissolved in dilute sulfuric

acid to produce a mixture of FeSO4 and Cr2(SO4)3. The FeSO4 reacts with K2Cr2O7 in acid
solution according to the following equation.
14H+
+ 6Fe2+ + Cr2O7
2– → 2Cr3+ + 6Fe3+ + 7H2O
When 1.00g of ferrochrome is dissolved in dilute sulfuric acid, and the resulting solution titrated,
13.1cm3
of 0.100moldm–3 K2Cr2O7 is required for complete reaction.
What is the percentage by mass of Fe in the sample of ferrochrome?
A 1.22 B 4.39 C 12.2 D 43.9

State with explanation.I tried all stuff with ionic equation but i couldn't find answer.

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1 answer

  1. mols K2Cr2O7 = M x L = 0.100 x 0.0131 =
    Convert to mols Fe this way.
    mols [Cr2O7]^2- x (6 mols Fe^2+/1 mol [Cr2O7]^2-) = ?
    Convert mols Fe to grams Fe. grams Fe = mols Fe x atomic mass Fe = ?
    Then %Fe = (grams Fe/mass sample)*100 = ?
    Post your work if you get stuck.

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