7.8 x 10^-3 = 0.0078 lb/qt
1lb = 454 g
0.0078 / 454 = 1.718061 x 10^-5 g/qt
Answer:
33.21% is the right answer.
Explanation:
0.04720 L * 0.02240 mol / L = 1.0573*10-3
mol Fe+2 = 1.0573* 10-3 mol = 5.2864*10-3
mass of Fe= 5.2864 * 10-3 = 0.29522g
% of Fe in sample = 0.29522 g Fe / 0.8890 g of sample * 100 = 33.21%