In the colorimetric (color producing) assay for iron used in this lab; potassium thiocyanate, KSCN, is added to produce a deep red colored precipitate. The lab outline suggests that H2O2 may be added to enhance the color. Write a balanced chemical equation showing the function of the peroxide. In your equation identify the oxidizing agent and the reducing agent.
Write a balanced chemical equation that describes the reaction of iron metal with HCl. Identify the oxidizing and reducing agents in your balanced equation.
Hey Maggieg11! Here is our balanced equation for the first reaction:
Fe+ KSCN+ H2O2----> FeO2 + KSCNH2
Next assign oxidation numbers for each. For the reactants Fe is 0, K is +1, SCN is -1, for the products Fe is +4, O2 is -2, K is +1, SCN is -1, H2 is +1. For rules on assigning oxidation numbers, check out Jule's video!
From these oxidation numbers we can see that Fe was oxidized because it went form having 0 charge to +4 charge, which also means its a reducing agent. And O2 was reduced as it went from having -1 charge to -2, which also means it is an oxidizing agent. For the second reaction of Fe with HCl set up your balanced equation: 2Fe + 6HCl ----> 2FeCl3 +3H2 and do the same thing using oxidation number rules. Hope that helped!