In the following question, a statement of Assertion (A) followed by a...
Reason (R): The dissociation/ ionisation of hydrogen sulphide in water is low in the presence of HCl due to common ion effect. It can be defined as a shift in equilibrium on adding a substance that provides more of an ionic species already present in the dissociation equilibrium.
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In the following question, a statement of Assertion (A) followed by a...
Assertion (A): The ionization of hydrogen sulphide in water is low in the presence of hydrochloric acid.
Reason (R): Hydrogen sulphide is a weak acid.
To understand the given assertion and reason, let's first discuss the ionization of hydrogen sulfide (H2S) in water.
Ionization of Hydrogen Sulfide (H2S) in Water:
When hydrogen sulfide is dissolved in water, it can undergo a partial ionization reaction:
H2S + H2O ⇌ H3O+ + HS-
In this reaction, a small fraction of hydrogen sulfide molecules ionize to produce hydronium ions (H3O+) and hydrogen sulfide ions (HS-). The extent of ionization depends on the equilibrium constant of the reaction, which is determined by the relative strengths of the acid (H2S) and the solvent (water).
Explanation of Assertion (A):
The statement in assertion (A) is that the ionization of hydrogen sulfide in water is low in the presence of hydrochloric acid. In other words, the presence of hydrochloric acid reduces the ionization of hydrogen sulfide.
Explanation of Reason (R):
The reason given in reason (R) is that hydrogen sulfide is a weak acid. This means that hydrogen sulfide does not completely ionize in water, resulting in a low concentration of hydronium ions (H3O+) and hydrogen sulfide ions (HS-).
Relationship between Assertion and Reason:
The reason provided does support the assertion. Since hydrogen sulfide is a weak acid, it does not readily ionize in water. When hydrochloric acid (a strong acid) is added to the system, it increases the concentration of hydronium ions (H3O+) and chloride ions (Cl-) in the solution. This shift in equilibrium reduces the ionization of hydrogen sulfide, leading to a lower concentration of hydronium ions (H3O+) and hydrogen sulfide ions (HS-).
Therefore, both the assertion and the reason are true, and the reason is a correct explanation of the assertion.
Conclusion:
The correct option is (A) Both A and R are true, and R is the correct explanation of A.
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