Final answer:
To rank the molecules CH2Cl2, CH3OH, and H2O from most to least polar, the order is H2O > CH3OH > CH2Cl2. Water is the most polar due to the bent shape and the high electronegativity of oxygen, creating strong polarity. Hydrophobicity rankings would be the reverse as polar molecules are less hydrophobic.
Step-by-step explanation:
The student's question involves ranking the polarity and hydrophobicity of the molecules CH2Cl2, CH3OH, and H2O. When ranking the polarity from most to least polar, we consider the electronegativity of the atoms and the shape of the molecule. Water (H2O) is the most polar due to its bent shape and the high electronegativity of oxygen, creating a significant dipole moment. Methanol (CH3OH) is next, with a polar O-H bond and a shape that allows for a dipole moment. Dichloromethane (CH2Cl2) is polar but less so than the others, due to its tetrahedral shape and less polar C-Cl bonds compared to the O-H bond in water and methanol. To circle the hydrophobic parts, we would focus on the nonpolar C-H bond regions in CH2Cl2 and the carbon chain in CH3OH. Considering hydrophobicity, the ranking from least to most hydrophobic would be H2O (5), CH3OH (4), CH2Cl2 (3). This ranking is based on the lack of nonpolar areas in water, a small hydrophobic portion in methanol, and the presence of two chlorines in dichloromethane, which increase its hydrophobic character due to their electronegativity being less than that of oxygen but more than carbon and hydrogen.