CHEMISTRY, M2 EQ-Bank 8 Calculate the concentration of sulfate ions present in a 750.0 mL aqueous solution containing 20.0 g of dissolved iron (III) sulfate. (3 marks) --- 6 WORK AREA LINES (style=lined) --- Show Answers Only \(0.200\ \text{mol L}^{-1}\) Show Worked Solution \(\ce{Fe2(SO4)3(s) -> 2Fe^{2+}(aq) + 3SO4^{2-}(aq)}\) \(n\ce{(Fe2(SO4)3)} = \dfrac{m}{MM} = \dfrac{20.00}{2(55.85) + 3(32.07) + 12(16.00)} = 0.0500\ \text{mol}\) The molar ratio of \(\ce{Fe2(SO4)3:SO4^{2-}}\) is \(1:3\) \(\therefore n\ce{(SO4^{2-})}= 3 \times 0.0500 = 0.1500\ \text{mol}\) \(c\ce{(SO4^{2-})} = \dfrac{0.1500}{0.75} = 0.200\ \text{mol L}^{-1}\)