Question

part 1 chromium is most commonly mined in the form of chromite, which has the chemical formula fecr2o4. calculate the percent by mass of each element in chromite, and give your answers to four significant digits. %fe = % %cr = % %o = % part 2 using the information from part 1, how much cr metal could be extracted from 173.1 g of chromite? round your answer to four significant digits. choose one: 80.42 g 43.19 g 40.21 g 49.49 g

Explanation:

Step1: Calculate molar mass of FeCr₂O₄

Molar mass of Fe ($M_{Fe}$) = 55.85 g/mol, Cr ($M_{Cr}$) = 52.00 g/mol, O ($M_{O}$) = 16.00 g/mol.
$M_{FeCr_2O_4}=M_{Fe}+2\times M_{Cr}+4\times M_{O}=55.85 + 2\times52.00+4\times16.00=55.85 + 104.00+64.00 = 223.85$ g/mol

Step2: Calculate %Fe

$\%Fe=\frac{M_{Fe}}{M_{FeCr_2O_4}}\times100=\frac{55.85}{223.85}\times100\approx24.95\%$

Step3: Calculate %Cr

$\%Cr=\frac{2\times M_{Cr}}{M_{FeCr_2O_4}}\times100=\frac{2\times52.00}{223.85}\times100=\frac{104.00}{223.85}\times100\approx46.45\%$

Step4: Calculate %O

$\%O=\frac{4\times M_{O}}{M_{FeCr_2O_4}}\times100=\frac{4\times16.00}{223.85}\times100=\frac{64.00}{223.85}\times100\approx28.60\%$

Step5: Calculate mass of Cr in 173.1 g of chromite for Part 2

Mass of Cr = $\%Cr\times$ mass of chromite.
Mass of Cr = $0.4645\times173.1 = 80.41495\approx80.42$ g

Answer:

%Fe = 24.95%
%Cr = 46.45%
%O = 28.60%
Part 2: 80.42 g