In which of the following compounds sulphur exhibit lowest oxidation state?
Answer & explanation
Correct answer: option 3
The correct answer is option 3. Hydrogen sulphide.
Let us delve into the oxidation states of sulphur in each compound mentioned to understand why hydrogen sulphide (\(H_2S\)) exhibits the lowest oxidation state among the options provided.
1. Sulphur Dioxide (\(SO_2\)):
In \(SO_2\), sulphur is bonded to two oxygen atoms. Oxygen typically exhibits an oxidation state of -2 in compounds (except in peroxides and superoxides). Therefore, to balance the charges:
\(2 \times (-2) + x = 0\)
\(x = +4\)
Thus, sulphur in \(SO_2\) has an oxidation state of +4.
2. Sulphur Monochloride (\(SCl_2\)):
In \(SCl_2\), sulfur is bonded to two chlorine atoms. Chlorine typically has an oxidation state of -1 in compounds (except in compounds with more electronegative atoms). Therefore, to balance the charges:
\(2 \times (-1) + x = 0\)
\(x = +2\)
Thus, sulphur in \(SCl_2\) has an oxidation state of +2.
3. Hydrogen Sulphide (\(H_2S\)):
In \(H_2S\), sulphur is bonded to two hydrogen atoms. Hydrogen typically exhibits an oxidation state of +1 in compounds. Therefore, to balance the charges:
\(2 \times (+1) + x = 0\)
\(x = -2\)
Thus, sulphur in \(H_2S\) has an oxidation state of -2.
4. Oleum (\(H_2SO_4\)):
Oleum is a solution of sulphur trioxide (\(SO_3\)) in concentrated sulphuric acid (\(H_2SO_4\)). In \(H_2SO_4\), sulphur typically has an oxidation state of +6 because sulphuric acid can be viewed as derived from sulphur trioxide:
\(\text{Sulphur in } SO_3: +6\)
\(\text{Sulphur in } H_2SO_4: +6\)
Among the compounds listed, hydrogen sulphide (\(H_2S\)) has the lowest oxidation state for sulfur, which is -2. This is because hydrogen sulphide (\(H_2S\)) contains sulphur in the form of \(S^{2-}\) ions, where sulphur exhibits its lowest oxidation state of -2 due to bonding with hydrogen atoms.
Therefore, the correct answer remains: (3) Hydrogen sulphide (\(H_2S\)).
This compound has sulphur in its lowest oxidation state among the options provided, illustrating the versatility of sulphur in different oxidation states depending on its chemical environment.