. Aluminum can be determined gravimetrically by reaction with a solution of 8-hy

Question

. Aluminum can be determined gravimetrically by reaction with a solution of 8-hydroxyquinoline (C9H7NO).   A mass of 0.1248 g of Al(C9H7NO)3 was obtained by precipitating all of the Al3+ from a solution prepared by dissolving 1.8571 g of a mineral. What is the mass percent of aluminum in the mineral?

2).A sample of an iron ore is dissolved in acid, and the iron is converted to Fe+2. The sample is then titrated with 47.20 mL of 0.02240 M MnO4- solution. The oxidation-reduction reaction that occurs during titration is:

8H+(aq) + MnO4-(aq) + 5Fe+2(aq) ® Mn+2(aq) + 5Fe+3(aq) + H2O(l)

A. How many moles of permanganate ion were added to the solution?

B. How many moles of iron(II) ion were in the sample?

C. How many grams of iron were in the sample?

D. If the sample had a mass of 0.8890 g, what is the percentage of iron in the sample?

Explanation / Answer

Mass of Al(C9H7NO)3 = 0.1248 g

=> Moles of Al(C9H7NO)3 = 0.1248 / 462.46 = 2.7 x 10^-4 moles

Moles of Al in 1 mole of Al(C9H7NO)3 = 1

Therefore moles of Al = 2.7 x 10^-4

=> Mass of Al = 2.7 x 10^-4 x 26.98 = 7.28 x 10^-3 g

Mass % of Al in the mineral = (7.28 x 10^-3 / 1.8571) x 100 = 0.392 %

2)

Moles of permanganate ion added to the solution = 0.0472 x 0.0224 = 1.0573 x 10^-3 moles

We see from the stoichiometry of the reaction that 1 mole of MnO4- reacts with 5 moles of Fe2+

Hence,

Moles of Fe2+ = 5 x 1.0573 x 10^-3 = 5.2864 x 10^-3 moles

Grams of Iron = 5.2864 x 10^-3 x 55.845 = 0.295 g

% iron = (0.295 / 0.889) x 100 = 33.2 %

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.