Question

which of the following is the stronger base?

• A. CH₃O^-
• B. CH₃COO^-
• C. CI^-
• D. OH^-

Answer 1

The Correct Option is A

The strength of a base is determined by the availability of the lone pair of electrons on the anion, which can accept a proton. Stronger bases have a higher tendency to donate electrons and accept protons.

- \( \text{CH}_3\text{O}^- \) (methoxide ion) is a strong base because the negative charge is on a small, highly electronegative oxygen atom with no stabilizing groups attached.

- \( \text{CH}_3\text{COO}^- \) (acetate ion) is weaker than \( \text{CH}_3\text{O}^- \) because the negative charge is delocalized between the two oxygen atoms, stabilizing the ion and reducing its basicity.

- \( \text{Cl}^- \) (chloride ion) is a very weak base because the negative charge is highly stabilized by the electronegativity of chlorine, making it unlikely to accept a proton.

- \( \text{OH}^- \) (hydroxide ion) is a strong base, but it is weaker than \( \text{CH}_3\text{O}^- \) because oxygen is less electron-rich in hydroxide compared to methoxide.

Thus, the strongest base among the given options is \( \text{CH}_3\text{O}^- \), which corresponds to option (A). 

Answer 2

The strength of a base is determined by the extent to which it can donate electrons or accept protons (H⁺). The stronger the conjugate acid of the base, the weaker the base is. The order of basicity of the given ions is based on the conjugate acids and the electron-donating ability of the species:

• \( \text{CH}_3\text{O}^- \) is the conjugate base of methanol (\( \text{CH}_3\text{OH} \)). This ion is a strong base because the alkoxide ion is a very strong electron donor.
• \( \text{CH}_3\text{COO}^- \) is the conjugate base of acetic acid. The resonance in this ion delocalizes the negative charge, making it weaker as a base.
• \( \text{C}^- \) is the conjugate base of methane (\( \text{CH}_4 \)), but it is highly unstable and does not act as a strong base.
• \( \text{OH}^- \) is the hydroxide ion, which is a strong base but less basic than the alkoxide ion (\( \text{CH}_3\text{O}^- \)).

Thus, \( \text{CH}_3\text{O}^- \) is the strongest base. Hence, the correct answer is (A).