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Multiple Choice
Which of the following compounds is the strongest acid?
A
Hydrochloric acid (HCl)
B
Water (H2O)
C
Phenol (C6H5OH)
D
Acetic acid (CH3COOH)
Verified step by step guidance
1
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 molecular structure and stability of the conjugate base: Strong acids have weak conjugate bases. Evaluate the stability of the conjugate base formed after the acid donates a proton.
Evaluate the electronegativity and bond strength: In hydrochloric acid (HCl), the bond between hydrogen and chlorine is highly polar due to chlorine's high electronegativity, making it easier for HCl to donate a proton.
Compare the acidity of the given compounds: Hydrochloric acid (HCl) is a strong acid, while water (H2O), phenol (C6H5OH), and acetic acid (CH3COOH) are weaker acids. HCl dissociates completely in water, indicating strong acidity.
Consider the pKa values: The pKa value is a measure of acid strength. Lower pKa values indicate stronger acids. Hydrochloric acid has a very low pKa compared to water, phenol, and acetic acid, confirming its status as the strongest acid among the options.