To determine the most polar bond in ethanol, [tex]\( CH_3CH_2OH \)[/tex], we need to analyze the electronegativity differences between the atoms in each bond. Here's a step-by-step solution to how we arrived at the answer:
1. Identify the Bonds:
Ethanol, [tex]\( CH_3CH_2OH \)[/tex], contains the following types of bonds:
- [tex]\( C-H \)[/tex]
- [tex]\( C-O \)[/tex]
- [tex]\( O-H \)[/tex]
- [tex]\( C-C \)[/tex]
2. Electronegativity Values:
We use the Pauling scale for electronegativity values of the atoms involved:
- Carbon ([tex]\( C \)[/tex]): 2.55
- Hydrogen ([tex]\( H \)[/tex]): 2.20
- Oxygen ([tex]\( O \)[/tex]): 3.44
3. Calculate Electronegativity Differences for Each Bond:
The electronegativity difference (ΔEN) helps us to understand the polarity of the bond. The differences are calculated as follows:
- For [tex]\( C-H \)[/tex] bond:
[tex]\[
\Delta EN = |2.55 - 2.20| = 0.35
\][/tex]
- For [tex]\( C-O \)[/tex] bond:
[tex]\[
\Delta EN = |2.55 - 3.44| = 0.89
\][/tex]
- For [tex]\( O-H \)[/tex] bond:
[tex]\[
\Delta EN = |3.44 - 2.20| = 1.24
\][/tex]
- For [tex]\( C-C \)[/tex] bond:
[tex]\[
\Delta EN = |2.55 - 2.55| = 0.0
\][/tex]
4. Determine the Most Polar Bond:
The bond with the highest electronegativity difference is considered the most polar. Comparing the values:
[tex]\[
\Delta EN_{O-H} = 1.24
\][/tex]
[tex]\[
\Delta EN_{C-O} = 0.89
\][/tex]
[tex]\[
\Delta EN_{C-H} = 0.35
\][/tex]
[tex]\[
\Delta EN_{C-C} = 0.0
\][/tex]
Among these, the [tex]\( O-H \)[/tex] bond has the highest electronegativity difference of 1.24, indicating that it is the most polar bond.
Therefore, in ethanol [tex]\( (CH_3CH_2OH) \)[/tex], the most polar bond is the [tex]\( O-H \)[/tex] bond.
The answer is:
B. [tex]\( O-H \)[/tex]
