Question

\[{{\rm{H}}_{\rm{2}}}{\rm{S}}\] is more acidic than \[{{\rm{H}}_{\rm{2}}}{\rm{O}}\] due to
A) O is more electronegative than S
B) O-H bond is stronger than S-H bond
C) O-H bond is weaker than S-H bond
D) None of these

Answer 1

Hint: According to Bronsted Lowry theory, donation of protons is by an acid and the hydroxide ions are donated by a base. An acid defines a species which donate a proton and a base is the one that can donate a hydroxide ion. The more acidic compound is the one that can donate the hydrogen ion easily.

Complete step by step solution:Let's understand the concept of electronegativity. It is the property of atoms to attract a shared electron pair towards itself. While considering the stronger acid, the more electronegative one has a stronger bond and it acts as a weaker acid.
Let's discuss the acidity of \[{{\rm{H}}_{\rm{2}}}{\rm{S}}\]and \[{{\rm{H}}_{\rm{2}}}{\rm{O}}\]. Here, the electronegativity is higher in case of oxygen than Sulphur. Therefore, O-H bond is stronger as comparison to S-H bond. Therefore, the S-H bond can be easily broken down than that of O-H bond. This energy is called the bond dissociation energy which is lower for the S-H bond. Thus, the H atom of S-H bond can be easily donated than O-H bond. Therefore, acidity of \[{{\rm{H}}_{\rm{2}}}{\rm{S}}\]is more than \[{{\rm{H}}_{\rm{2}}}{\rm{O}}\].

Therefore, the nature of the O-H bond is stronger than the S-H bond.

Hence, option B is right.

Note: There are many theories that define acids and bases such as Arrhenious theory, Bronsted-Lowry acid, Lewis theory etc. According to Arrhenious theory, an acid can donate protons and a base can donate hydroxide ions in aqueous solutions.