4. which intermolecular force is responsible for the unique properties of water? a) london dispersion b) ion–dipole c) hydrogen bonding d) dipole–dipole explain:______________________________ 5. what is the shape of carbon dioxide (co₂)? a) bent b) trigonal planar c) linear d) tetrahedral explain:______________________________ part b: explain and discuss (minimum of 5 sentences) 3. explain in terms of intermolecular forces why water striders can walk on water without sinking. (10 points) 4. explain in terms of polarity why water and oil cannot mix. (10 points)

Question

Accepted Answer

### Question 4 (Intermolecular Forces of Water)
# Brief Explanations:
Water has highly electronegative oxygen bonded to hydrogen, creating polar O-H bonds. The partially positive H atoms form strong attractions to partially negative O atoms in adjacent water molecules. This unique, strong intermolecular force gives water properties like high boiling point, surface tension, and high specific heat.
# Answer:
C) Hydrogen bonding

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### Question 5 (CO₂ Molecular Shape)
# Brief Explanations:
Carbon dioxide has a central carbon atom double-bonded to two oxygen atoms. There are no lone electron pairs on the central carbon, so the bonding pairs arrange themselves to maximize distance, resulting in a straight, symmetric geometry.
# Answer:
C) Linear

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### Part B Question 3 (Water Striders on Water)
# Brief Explanations:
Water exhibits strong hydrogen bonding between its molecules. These intermolecular attractions create a cohesive network of water molecules at the surface, forming a thin, rigid "skin" known as surface tension. Water striders have specialized, hydrophobic (water-repellent) legs that distribute their body weight evenly across a large surface area. The surface tension of water is strong enough to support the insect's small mass without breaking the cohesive molecular layer. When the water strider's legs press on the surface, the water molecules dip slightly but do not separate, allowing the insect to walk across the surface instead of sinking. Additionally, the hydrophobic nature of their legs prevents them from becoming wet, which would disrupt the surface tension and cause them to submerge.
# Answer:
Water striders can walk on water due to the strong surface tension created by water's hydrogen bonding. Hydrogen bonds form a cohesive, interconnected network of water molecules at the air-water interface, creating a rigid surface layer. The water strider's lightweight body and specialized hydrophobic legs distribute its weight evenly over a large area, avoiding breaking the surface tension. The hydrophobic legs repel water, preventing the insect from becoming submerged and maintaining the integrity of the surface layer it stands on. This combination of water's cohesive intermolecular forces and the insect's physical adaptations allows it to stay atop the water without sinking.

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### Part B Question 4 (Water and Oil Immiscibility)
# Brief Explanations:
Water is a highly polar molecule: the electronegative oxygen atom pulls electron density away from the hydrogen atoms, creating partial positive and negative charges on the molecule. Oil molecules, by contrast, are nonpolar (composed of nonpolar carbon-hydrogen bonds with evenly distributed electron density). The principle "like dissolves like" governs miscibility: polar substances interact favorably with other polar substances, and nonpolar substances interact favorably with other nonpolar substances. Polar water molecules form strong hydrogen bonds with each other, and nonpolar oil molecules form weak London dispersion forces with each other. When mixed, water molecules are more attracted to each other than to nonpolar oil molecules, and oil molecules are more attracted to each other than to water molecules. This causes the two substances to separate into distinct layers, with the less dense oil floating on top of the denser water, as there is no sufficient intermolecular attraction between polar and nonpolar molecules to form a homogeneous mixture.
# Answer:
Water and oil cannot mix due to differences in their polarity, following the "like dissolves like" rule. Water is a highly polar molecule, with partial positive charges on its hydrogen atoms and a partial negative charge on its oxygen, leading to strong hydrogen bonding between water molecules. Oil is composed of nonpolar hydrocarbon molecules, which have evenly distributed electron density and only weak London dispersion forces between them. Polar water molecules are far more attracted to other polar water molecules than to nonpolar oil molecules, and nonpolar oil molecules prefer interacting with other oil molecules. When combined, the two substances do not form favorable intermolecular interactions, so they separate into distinct layers (oil on top, as it is less dense) instead of forming a homogeneous mixture.

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QUESTION IMAGE

Question

Explanation:

Question 4 (Intermolecular Forces of Water)

Answer:

Question 5 (CO₂ Molecular Shape)