An environmental chemist needs to determine the amount of Fe+2 ions in a simple of polluted water from a rusting industrial plant. one procedure is to analyses the sample by using solution of sodium dochromate, Na2Cr2O7. identify the oxdising agent and the reducing agent in the following reaction: Na2CrO7(aq) + Fe2+(aq) + He+(aq)----Fe+3(aq) + Cr3+(aq) + H2o(l) + Na+(aq)...balance the above reaction.
To identify the oxidizing agent and the reducing agent in the given reaction, we need to understand the concept of oxidation and reduction.
Oxidation is the process of losing electrons, while reduction is the process of gaining electrons. In a redox (reduction-oxidation) reaction, there is always an oxidizing agent and a reducing agent.
In the given reaction:
Na2Cr2O7(aq) + Fe2+(aq) + He+(aq) → Fe3+(aq) + Cr3+(aq) + H2O(l) + Na+(aq)
We need to determine which species is being oxidized and which one is being reduced.
The species that loses electrons is the reducing agent, and the species that gains electrons is the oxidizing agent.
In this reaction:
Fe2+(aq) → Fe3+(aq)
Here, Fe2+ loses an electron and gets oxidized to Fe3+. Therefore, Fe2+ is the reducing agent.
Na2Cr2O7(aq) → Cr3+(aq)
In this case, Cr in Na2Cr2O7 gains electrons and gets reduced from Cr6+ to Cr3+. Therefore, Na2Cr2O7 is the oxidizing agent.
To balance the equation, we need the same number of each element on both sides. Here's the balanced equation:
2Na2Cr2O7(aq) + 6Fe2+(aq) + 14H+(aq) → 6Fe3+(aq) + 4Cr3+(aq) + 7H2O(l) + 4Na+(aq)
In this balanced reaction, we see that 6 molecules of Fe2+ react with 2 molecules of Na2Cr2O7.
Please note that the question mentions He+(aq), but as a chemical symbol, "He" represents helium, which is inert and does not participate in chemical reactions. It might be a typo, and we can ignore it for the purpose of balancing the reaction.