Question

1. for each of the molecules below, draw the compound using a lewis structure and then indicate whether that molecule is polar or nonpolar. ch₄ nh₃ oh⁻ 9. answer the following questions using the diagram below: methanol and ethane are mixed with water: a. which molecule(s) are polar? what led you to this conclusion? b. which molecule(s) are nonpolar? what led you to this conclusion? c. which molecule is \water - fearing\ or \hydrophobic\? what led you to this conclusion? d. which molecule is \water - loving\ or \hydrophilic\? what led you to this conclusion?

Explanation:

Step1: Analyze CH₄

Carbon has 4 valence - electrons and hydrogen has 1. In CH₄, carbon forms 4 single bonds with 4 hydrogen atoms. The Lewis structure has carbon in the center with 4 hydrogen atoms around it. The molecule has a tetrahedral shape. Since the electronegativity difference between C and H is small and the molecule is symmetric, CH₄ is non - polar.

Step2: Analyze NH₃

Nitrogen has 5 valence - electrons. In NH₃, nitrogen forms 3 single bonds with 3 hydrogen atoms and has 1 lone pair of electrons. The Lewis structure has nitrogen in the center with 3 hydrogen atoms and a lone pair. The molecule has a trigonal pyramidal shape. Due to the presence of the lone pair and the electronegativity difference between N and H, NH₃ is polar.

Step3: Analyze OH⁻

Oxygen has 6 valence - electrons and hydrogen has 1. In OH⁻, oxygen forms a single bond with hydrogen and has 3 lone pairs of electrons. The Lewis structure has oxygen with a hydrogen atom and 3 lone pairs. The electronegativity difference between O and H and the non - symmetric shape make OH⁻ polar.

Step4: Analyze methanol (CH₃OH)

In methanol, the carbon atom is bonded to 3 hydrogen atoms and an - OH group. The oxygen in the - OH group has 2 lone pairs. The molecule has a polar C - O bond and an O - H bond due to the high electronegativity of oxygen. The presence of these polar bonds and the non - symmetric shape make methanol polar.

Step5: Analyze ethane (C₂H₆)

Each carbon atom in ethane is bonded to 3 hydrogen atoms and to the other carbon atom. The electronegativity difference between C and H is small, and the molecule is symmetric. So, ethane is non - polar.

Step6: Answer question 9a

Polar molecules are NH₃, OH⁻, and methanol. The presence of lone pairs and electronegativity differences create a net dipole moment in these molecules.

Step7: Answer question 9b

Non - polar molecules are CH₄ and ethane. They have either small electronegativity differences or are symmetric, resulting in no net dipole moment.

Step8: Answer question 9c

Ethane is hydrophobic. Hydrophobic molecules are non - polar, and ethane's non - polarity means it does not interact well with polar water molecules.

Step9: Answer question 9d

Methanol is hydrophilic. It is polar and can form hydrogen bonds with water molecules due to the presence of the - OH group.

Answer:

For question 8:
CH₄: Non - polar
NH₃: Polar
OH⁻: Polar
For question 9a:
Polar molecules: NH₃, OH⁻, methanol. Reason: Presence of lone pairs and electronegativity differences creating a net dipole moment.
For question 9b:
Non - polar molecules: CH₄, ethane. Reason: Small electronegativity differences or symmetry resulting in no net dipole moment.
For question 9c:
Ethane is hydrophobic. Reason: It is non - polar and does not interact well with polar water.
For question 9d:
Methanol is hydrophilic. Reason: It is polar and can form hydrogen bonds with water due to the - OH group.