Final answer:
Without the calculated dipole moment for a purely ionic HF bond, a precise calculation can't be made. Comparatively, HF may have a slightly higher percent ionic character than HCl, due to its higher experimental dipole moment. The estimated answer is likely (option B) 20%, more ionic.
Step-by-step explanation:
To calculate the percent ionic character of the H−F bond, we can use the formula: percent ionic character = (experimental dipole moment / calculated dipole moment for a 100% ionic bond) × 100%.
The question mentions that HF has a dipole moment (μ) of 1.83 D and a bond length of 92 pm. To find the calculated dipole moment for a 100% ionic bond, we take the charge of an electron (1.60218 × 10⁻¹⁹C) and multiply by the bond distance in meters (92 pm = 92 × 10⁻¹²m). The result would be the dipole moment if HF were 100% ionic.
Let's do the calculation:
- Calculated dipole moment for 100% ionic bond = (1.60218 × 10⁻¹⁹C) × (92 × 10⁻¹²m)
- Converting this to Debye (D), we use the conversion 1 D = 3.336 × 10⁻³⁰ C−m
However, since we don't have the exact calculated dipole moment for a 100% ionic HF bond, we cannot directly complete the calculation. We need this value to compare to the experimental value given (1.83 D). Typically, the calculated dipole moment for a purely ionic bond is around 6-10 D, depending on the specific bond. Assuming the hypothetical purely ionic dipole moment of HF is similar to that, the 1.83 D experimental value indicates that HF is much less than 100% ionic, likely in the range of 18% to 30%, as seen with molecules like HCl.
In the textbook worked example (HCl), the dipole moment is 1.08 D and the bond length is 127.5 pm. Applying the same calculation for HCl gives us a percent ionic character of approximately 17-18% for HCl.
Comparing the two, assuming HCl has 17-18% ionic character and HF has a similar or slightly higher ionic character (being a smaller molecule with a higher charge density), we can tentatively suggest that HF might have a slightly higher percent ionic character than HCl, but without the exact calculated value for HF's purely ionic dipole moment, we can't be precise. Therefore, the closest estimate given the choices would be (option B) 20%, more ionic because HF has a higher dipole moment than HCl, indicating potentially greater ionic character. However, please note that this is only a estimate.