Question

Rank the following molecules from most basic to least basic:

(a) NH3
(b) CH4
(c) H2O
(d) HF

Answer 1

The molecules ranked from most basic to least basic are NH3 (most basic), H2O, CH4, and HF (least basic). NH3 is more basic because it readily accepts a proton, whereas HF is least basic due to its strong acidity and very stable conjugate base.

Step-by-step explanation:

To rank the molecules from most basic to least basic, we must consider their ability to accept protons, according to the Brønsted-Lowry concept of acids and bases. The basicity of a molecule is correlated with the stability of its conjugate acid. Stronger bases have weaker conjugate acids. Let's look at the given molecules:

• NH3 (Ammonia)
• H2O (Water)
• CH4 (Methane)
• HF (Hydrofluoric Acid)

Ammonia is known to be a better proton acceptor than water, making it more basic. Methane, although it has a conjugate base of CH3⁻, is less willing to accept a proton due to carbon's lower electronegativity. Fluorine's high electronegativity in HF makes its conjugate base very stable, thus HF is a weak base but a strong acid. Therefore, the order from most basic to least basic is:

1. NH3
2. H2O
3. CH4
4. HF

With this understanding, HF is the least basic due to its strong acidity, and NH3 is the most basic as it more readily accepts a proton.