What is the systematic name of the acid H2S?
a) hydrosulfuric acid
b) sulfuric acid
c) sulfurous acid
d) hydrosulfurous acid
e) hyposulfuric acid
The correct answer and explanation is:
The correct answer is:
a) hydrosulfuric acid
Explanation:
The acid H₂S is commonly known as hydrosulfuric acid, also often called hydrogen sulfide when in gaseous form. Let’s break down why this is the correct systematic name and why the other options are incorrect.
Understanding the Naming of H₂S:
- Composition of H₂S:
H₂S consists of hydrogen and sulfur. It is a binary acid (only two elements: hydrogen and a nonmetal sulfur). - Binary Acids Naming Convention:
Binary acids are acids composed of hydrogen and one other nonmetal element. The naming system for binary acids is:- Prefix “hydro-“
- Stem name of the nonmetal + “-ic” suffix
- The word “acid”
- Application to H₂S:
Sulfur is the nonmetal here. The stem for sulfur is “sulfur-“. Following the binary acid naming rules, the name becomes hydrosulfuric acid.
Why not the other options?
- b) sulfuric acid (H₂SO₄):
This is a well-known acid, but it contains sulfur and oxygen, not just hydrogen and sulfur. The formula H₂SO₄ corresponds to sulfuric acid, a strong oxyacid, not H₂S. - c) sulfurous acid (H₂SO₃):
This is another oxyacid of sulfur, containing oxygen. It has the formula H₂SO₃, not H₂S. - d) hydrosulfurous acid:
This is not a standard or systematic name recognized in chemistry. The “ous” suffix is used in oxyacids to denote a lower oxidation state of the central atom but does not apply to binary acids like H₂S. - e) hyposulfuric acid:
This refers to an acid with a prefix “hypo-” meaning “less” or “below,” used in naming certain oxyacids of halogens or sulfur in specific oxidation states, but it is not applicable for H₂S.
Summary:
- H₂S is a binary acid (H + S).
- Binary acids are named with “hydro-” + nonmetal stem + “-ic” + acid.
- Hence, H₂S is hydrosulfuric acid.
- Other options are oxyacids or incorrectly named acids.
In conclusion, the systematic and correct name for H₂S is hydrosulfuric acid (option a).