5. Identify whether the following reaction is an oxidation or a reduction.
a. Ni2+ + 2e- �¨ Ni
b. 2Br- �¨ Br2 + 2e-
c. O2 + 4e- �¨ 2O2-
d. Zn �¨ 2e- + Zn2+
e. H2 �¨ 2H+ + 2e-
See your post above for definitions of oxidation and reduction.
To determine whether a reaction is an oxidation or a reduction, you need to identify the changes in the oxidation states of the elements involved.
In an oxidation reaction, an element loses electrons, resulting in an increase in its oxidation state. In a reduction reaction, an element gains electrons, leading to a decrease in its oxidation state.
Let's go through each reaction to determine whether it is an oxidation or reduction:
a. Ni2+ + 2e- → Ni
In this reaction, Ni2+ gains 2 electrons to become Ni. Since the oxidation state of nickel decreases from +2 to 0, this reaction is a reduction.
b. 2Br- → Br2 + 2e-
In this reaction, Br- loses 2 electrons to form Br2. The oxidation state of bromine increases from -1 to 0, indicating that this reaction is an oxidation.
c. O2 + 4e- → 2O2-
In this reaction, O2 gains 4 electrons to form O2-. The oxidation state of oxygen decreases from 0 to -2, confirming that this reaction is a reduction.
d. Zn → 2e- + Zn2+
In this reaction, zinc loses 2 electrons to form Zn2+. The oxidation state of zinc increases from 0 to +2, indicating that this reaction is an oxidation.
e. H2 → 2H+ + 2e-
In this reaction, H2 loses 2 electrons to form 2H+. The oxidation state of hydrogen increases from 0 to +1, showing that this reaction is an oxidation.
To summarize:
a. Reduction
b. Oxidation
c. Reduction
d. Oxidation
e. Oxidation