Question

How do I prepare a solution of 0.0025M Fe3+ by dissolving the appropriate amount of ferric ammonium sulfate in 500 cm^3 of 0.0025M sulfuric acid?

Answer 1

Ferric ammonium sulfate is Fe3(NH4)2(SO4)3. Look up the molar mass,multiply by 0.0025 to get the moles needed for a liter of solution. Since there are 3 moles Fe^+3 per mole of Fe3(NH4)2(SO4)3, divide by 3 to find the amount necessary for moles Fe^+3, then divide by 2 since you only want to prepare 500 cc solution.