metals with 8-hydroxyquinoline, C9H7NO. After weighing the mixed precipitate, the precipitate is dissolved and the amount of 8-hydroxyquinoline determined by another method. In a typical analysis, a 127.3 mg sample of an alloy containing iron, manganese, and other metals was dissolved in acid and treated with appropriate masking agents to prevent interference from other metals. The iron and manganese were precipitated and isolated as Fe(C9H6NO)3 and Mn(C9H6NO)2, yielding a total mass of 867.8 mg. The amount of 8-hydroxyquinolate in the mixed precipitate was determined to be 5.276 mmol. Calculate the %w/w Fe and %w/w Mn in the alloy
To calculate the percent by weight (%w/w) of iron (Fe) and manganese (Mn) in the alloy, you'll need to use the given information about the mass of the mixed precipitate and the amount of 8-hydroxyquinolate in it.
Let's start with the calculation for Fe:
1. Determine the mass of Fe(C9H6NO)3. From the balanced chemical equation, we know that Fe(C9H6NO)3 contains one mole of Fe for every three moles of C9H7NO.
- Molar mass of Fe(C9H6NO)3 = 3 × molar mass of C9H6NO + molar mass of Fe
- Molar mass of C9H6NO = 9 × atomic mass of C + 6 × atomic mass of H + atomic mass of N + atomic mass of O
- Molar mass of Fe = atomic mass of Fe
2. Calculate the number of moles of Fe(C9H6NO)3:
- Moles of Fe(C9H6NO)3 = mass of Fe(C9H6NO)3 / molar mass of Fe(C9H6NO)3
3. Calculate the number of moles of Fe:
- Moles of Fe = moles of Fe(C9H6NO)3 × (1 mole of Fe / 3 moles of C9H7NO)
4. Calculate the mass of Fe:
- Mass of Fe = moles of Fe × molar mass of Fe
To calculate the percent by weight of Fe, divide the mass of Fe by the initial mass of the alloy and multiply by 100:
Percent by weight of Fe = (Mass of Fe / Initial mass of alloy) × 100%
Repeat the same steps for Mn to calculate its percent by weight.
Note: The molar mass values and atomic masses can be found in the periodic table or a chemistry reference book.