The molecule CH3CH2OH, commonly known as ethanol, is a polar molecule.
This polarity arises from the presence of the hydroxyl group (-OH) in its structure. The oxygen atom in the hydroxyl group is more electronegative than the hydrogen and carbon atoms. This difference in electronegativity causes the electrons in the O-H bond to be drawn closer to the oxygen atom, creating a partial negative charge (δ-) at the oxygen and a partial positive charge (δ+) at the hydrogen. As a result, the molecule has a dipole moment with one end being slightly negative and the other slightly positive.
On the other hand, the carbon chain (CH3CH2-) is relatively nonpolar due to the similar electronegativities of carbon and hydrogen. However, because of the significant electronegative oxygen in the hydroxyl group, the overall molecule does not cancel out its dipole moments, making ethanol polar.
In summary, CH3CH2OH is polar due to the presence of the polar O-H bond that creates a distinguishable dipolar character in the molecule.