For the reaction, shown below, determine which statements are True and which are False.
3Fe(s) + Cr2O72-(aq) +14H+(aq) → 3Fe2+(aq) + 2Cr3+(aq) + 7H2O(l) ξo=1.77V
1. The oxidizing agent is dichromate (Cr2O72-).
2. The iron half-reaction takes place in an acidic solution.
3. The oxidation state of chromium in dichromate is +3.
4. The oxidation state of hydrogen changes from 0 to +1.
5. The highest oxidation state for hydrogen in this reaction is 0
6. The reducing agent is Fe (s)
1. False. The oxidizing agent is the species that gets reduced, so in this case, it is chromium (Cr2O72-).
2. True. The presence of H+ ions in the reaction shows that it takes place in an acidic solution.
3. False. The oxidation state of chromium in dichromate is +6.
4. False. The oxidation state of hydrogen changes from +1 to 0. It is reduced in this reaction, not oxidized.
5. False. The highest oxidation state for hydrogen in this reaction is +1, not 0.
6. True. Fe(s) is being oxidized, so it is acting as the reducing agent.
1. False. The oxidizing agent is the species that causes another species to undergo oxidation by accepting electrons. In this reaction, the iron (Fe) is being oxidized, so the oxidizing agent is Cr2O72-.
2. True. The presence of H+ ions in the reaction indicates that it takes place in an acidic solution.
3. False. The oxidation state of chromium in dichromate (Cr2O72-) is +6. In this reaction, it is reduced from +6 to +3.
4. True. The oxidation state of hydrogen changes from 0 to +1 in this reaction. The water molecules (H2O) formed have hydrogen with an oxidation state of +1.
5. False. The highest oxidation state for hydrogen in this reaction is +1. Hydrogen cannot have an oxidation state of 0 in this reaction.
6. True. The reducing agent is the species that causes another species to undergo reduction by losing electrons. In this reaction, Fe (s) loses electrons and is oxidized, so it is the reducing agent.
To determine which statements are true and false, let's analyze each statement:
1. The oxidizing agent is dichromate (Cr2O72-): TRUE
To determine the oxidizing agent, look for the species that gets reduced in the redox reaction. In this case, Cr2O72- gains electrons and is reduced to Cr3+, so it acts as an oxidizing agent.
2. The iron half-reaction takes place in an acidic solution: TRUE
The presence of H+ in the reaction indicates that the reaction takes place in an acidic solution.
3. The oxidation state of chromium in dichromate is +3: FALSE
The oxidation state of chromium in dichromate (Cr2O72-) is +6, not +3. Each oxygen has an oxidation state of -2, and since there are seven oxygen atoms in dichromate, the overall charge contributed by oxygen is -14. Since the overall charge of dichromate is -2, the oxidation state of chromium is +6 to balance the charges.
4. The oxidation state of hydrogen changes from 0 to +1: TRUE
In the reaction, hydrogen in H+ changes its oxidation state from 0 to +1.
5. The highest oxidation state for hydrogen in this reaction is 0: FALSE
The highest oxidation state for hydrogen in this reaction is +1, considering the oxidation state of H+ in the reaction.
6. The reducing agent is Fe (s): TRUE
To determine the reducing agent, look for the species that gets oxidized in the redox reaction. In this case, Fe(s) loses electrons and is oxidized to Fe2+, so it acts as the reducing agent.
So, the correct answer is:
1. True
2. True
3. False
4. True
5. False
6. True