Identify all the species that got oxidized and reduced in the reactions below.
a. NaOH (aq) + HCl (aq) ----→ NaCl (aq) + H2O (l)
b. Fe (s) + CuCl2 (aq) -------→ FeCl2 (aq) + Cu (s)
c. Cr2O7 2- (aq) + Cl- (aq) -----→ Cr3+ (aq) + Cl2(g)
Hydrogen-atom transfer
Hydrazine, losing hydrogen, is oxidized to molecular nitrogen, while oxygen, gaining hydrogen, is reduced to water.
When an oxidation number of an atom is increased in the course of a redox reaction, that atom is being oxidized. When an oxidation number of an atom is decreased in the course of a redox reaction, that atom is being reduced.
So, hearing this information, how will you solve your problem?
a. I don't see any increase or decrease in atoms for this one. Is this a non-redox reaction?
b. Fe is the reduced and Cu is oxidized?
c. Cr is oxidized and Cl is reduced?
I'm confused about hydrazine and N2. Don't see any in the problem.
There is no oxidation/reduction in a.
In b Fe is oxidized and Cu^2+ is reduced. Note the Fe INCREASES oxidation number from zero to 2+ and Cu DECREASES from 2+ to zero. In c, Cr is reduced (EACH Cr goes from oxidation state of 6+ to 3+ so it DECREASES while Cl goes from 1- to zero so it INCREASES.
a. In the reaction NaOH (aq) + HCl (aq) ----→ NaCl (aq) + H2O (l), sodium (Na) is oxidized from the +1 oxidation state to 0, while chlorine (Cl) is reduced from -1 to 0.
b. In the reaction Fe (s) + CuCl2 (aq) -------→ FeCl2 (aq) + Cu (s), iron (Fe) is oxidized from 0 to +2, while copper (Cu) is reduced from +2 to 0.
c. In the reaction Cr2O7 2- (aq) + Cl- (aq) -----→ Cr3+ (aq) + Cl2(g), chromium (Cr) is reduced from +6 to +3, while chloride (Cl) is oxidized from -1 to 0.
To determine the species that got oxidized and reduced in each reaction, we need to identify the element that experienced a change in its oxidation number.
a. NaOH (aq) + HCl (aq) ----→ NaCl (aq) + H2O (l)
In this reaction, Na (sodium) and Cl (chlorine) are the elements present. The oxidation number of sodium is +1, and the oxidation number of chlorine is -1. However, in NaCl, the oxidation number of sodium is still +1, and the oxidation number of chlorine is still -1, indicating that there was no change in oxidation numbers. Therefore, no species got oxidized or reduced in this reaction.
b. Fe (s) + CuCl2 (aq) -------→ FeCl2 (aq) + Cu (s)
In this reaction, Fe (iron) and Cu (copper) are the elements present. The oxidation number of iron is 0, and the oxidation number of copper in CuCl2 is +2. In the product FeCl2, the oxidation number of iron is +2, while the oxidation number of copper in Cu is 0. The oxidation number of iron changed from 0 to +2, indicating that it got oxidized. The oxidation number of copper changed from +2 to 0, indicating that it got reduced. Therefore, iron got oxidized, and copper got reduced in this reaction.
c. Cr2O7 2- (aq) + Cl- (aq) -----→ Cr3+ (aq) + Cl2(g)
In this reaction, Cr (chromium) and Cl (chlorine) are the elements present. The oxidation number of chromium in Cr2O7 2- is +6, and the oxidation number of chlorine in Cl- is -1. In the product Cr3+, the oxidation number of chromium is +3, while in Cl2, the oxidation number of chlorine is 0. The oxidation number of chromium changed from +6 to +3, indicating that it got reduced. The oxidation number of chlorine changed from -1 to 0, indicating that it got oxidized. Therefore, chromium got reduced, and chlorine got oxidized in this reaction.
To summarize:
a. No species got oxidized or reduced.
b. Iron got oxidized, and copper got reduced.
c. Chromium got reduced, and chlorine got oxidized.