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Multiple Choice
Which of the following compounds is the strongest acid?
A
Water (H2O)
B
Phenol (C6H5OH)
C
Hydrochloric acid (HCl)
D
Acetic acid (CH3COOH)
Verified step by step guidance
1
Identify the functional groups present in each compound: Water (H2O) has no functional group, Phenol (C6H5OH) has a hydroxyl group attached to an aromatic ring, Hydrochloric acid (HCl) is a strong acid with a halogen, and Acetic acid (CH3COOH) has a carboxylic acid group.
Understand the concept of acidity: Acidity is determined by the ability of a compound to donate a proton (H+). The stronger the acid, the more readily it donates a proton.
Consider the strength of the acids: Hydrochloric acid (HCl) is a strong acid, meaning it completely dissociates in water to release protons. Acetic acid (CH3COOH) is a weak acid, partially dissociating in water. Phenol (C6H5OH) is even weaker, and water (H2O) is the weakest among these.
Evaluate the stability of the conjugate base: The more stable the conjugate base, the stronger the acid. HCl forms Cl-, which is a very stable conjugate base due to its high electronegativity and ability to disperse charge.
Compare the acidity: Based on the ability to donate protons and the stability of the conjugate base, Hydrochloric acid (HCl) is the strongest acid among the given compounds.