In order to determine if the given chemical reaction is an oxidation-reduction (redox) reaction, we need to analyze whether there is a transfer of electrons between the reactants, which results in a change in oxidation states of the elements involved.
Here's the reaction given:
[tex]\[ \text{CuSO}_4 + \text{Na}_2\text{S} \rightarrow \text{CuS} + \text{Na}_2\text{SO}_4 \][/tex]
Let's analyze the oxidation states of the elements in the reactants and products:
1. Copper sulfate ([tex]\(\text{CuSO}_4\)[/tex]):
- Copper ([tex]\(\text{Cu}\)[/tex]) typically has an oxidation state of [tex]\(+2\)[/tex].
- Sulfate ion ([tex]\(\text{SO}_4^{2-}\)[/tex]) has [tex]\(+6\)[/tex] for sulfur and [tex]\(-2\)[/tex] for each oxygen (total charge of [tex]\(-2\)[/tex]).
2. Sodium sulfide ([tex]\(\text{Na}_2\text{S}\)[/tex]):
- Sodium ([tex]\(\text{Na}\)[/tex]) typically has an oxidation state of [tex]\(+1\)[/tex].
- Sulfur ([tex]\(\text{S}\)[/tex]) typically has an oxidation state of [tex]\(-2\)[/tex].
3. Copper sulfide ([tex]\(\text{CuS}\)[/tex]):
- Copper ([tex]\(\text{Cu}\)[/tex]) typically has an oxidation state of [tex]\(+2\)[/tex].
- Sulfur ([tex]\(\text{S}\)[/tex]) typically has an oxidation state of [tex]\(-2\)[/tex].
4. Sodium sulfate ([tex]\(\text{Na}_2\text{SO}_4\)[/tex]):
- Sodium ([tex]\(\text{Na}\)[/tex]) typically has an oxidation state of [tex]\(+1\)[/tex].
- Sulfate ion ([tex]\(\text{SO}_4^{2-}\)[/tex]) has [tex]\(+6\)[/tex] for sulfur and [tex]\(-2\)[/tex] for each oxygen (total charge of [tex]\(-2\)[/tex]).
Now, let’s compare the oxidation states of each element in the reactants and products:
- Copper ([tex]\(\text{Cu}\)[/tex]) remains [tex]\(+2\)[/tex] in both [tex]\(\text{CuSO}_4\)[/tex] and [tex]\(\text{CuS}\)[/tex].
- Sodium ([tex]\(\text{Na}\)[/tex]) remains [tex]\(+1\)[/tex] in both [tex]\(\text{Na}_2\text{S}\)[/tex] and [tex]\(\text{Na}_2\text{SO}_4\)[/tex].
- Sulfur ([tex]\(\text{S}\)[/tex]) in [tex]\(\text{Na}_2\text{S}\)[/tex] ([tex]\(-2\)[/tex]) changes to [tex]\(\text{CuS}\)[/tex] ([tex]\(-2\)[/tex]) and [tex]\(\text{SO}_4\)[/tex] ([tex]\(+6\)[/tex]) remains the same.
There is no change in oxidation states for copper, sodium, and sulfur between the reactants and the products. Since there is no change in the oxidation states, this means that there is no transfer of electrons, and therefore, this reaction is not a redox reaction.
Hence, the correct answer is:
D. This is not a redox reaction because no electrons were transferred.
