A) Calculate the mass concentration of iron (II). b) Explain why the solution was acidified with H2SO4 instead of HCl.

In redox titrations, especially those involving strong oxidizing agents (like potassium permanganate, which is commonly used to titrate iron(II)), sulfuric acid ($\text{H}_2\text{SO}_4$) is preferred over hydrochloric acid ($\text{HCl}$) for acidification.

• Hydrochloric acid ($\text{HCl}$): Contains chloride ions ($\text{Cl}^-$) which can be oxidized by strong oxidizing agents to chlorine gas ($\text{Cl}_2$). This side reaction would interfere with the main titration, leading to inaccurate results.
• Sulfuric acid ($\text{H}_2\text{SO}_4$): Its sulfate ions ($\text{SO}_4^{2-}$) are not easily oxidized and therefore do not interfere with the redox reaction, making it a suitable acid for such titrations.