Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Covalent Bonds

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Covalent Bonds

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3:21 minutes

Problem 23

Textbook Question

Explain why, if you pour water into a glass very carefully, you can 'stack' the water slightly above the rim of the glass.

Verified step by step guidance

Understand the concept of surface tension: Surface tension is a property of liquids caused by the cohesive forces between molecules at the surface. Water molecules at the surface experience a net inward force due to hydrogen bonding, creating a 'skin-like' effect that resists external forces.

Recognize the role of cohesion in water: Water molecules are polar, meaning they have a partial positive charge on one side (hydrogen) and a partial negative charge on the other side (oxygen). This polarity leads to strong intermolecular hydrogen bonds, which contribute to water's high surface tension.

Visualize the stacking effect: When you pour water carefully into a glass, the cohesive forces between water molecules allow the liquid to form a dome-like shape above the rim. The surface tension acts to hold the water together, preventing it from spilling over immediately.

Consider the balance of forces: The water remains stacked above the rim as long as the cohesive forces (surface tension) are stronger than the gravitational forces pulling the water downward. Pouring carefully minimizes disturbances that could break the surface tension and cause the water to spill.

Understand the limits of stacking: Eventually, if you add too much water, the gravitational force will overcome the surface tension, causing the water to spill over the rim. This demonstrates the balance between cohesive forces and external forces acting on the liquid.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Surface Tension

Surface tension is the cohesive force between liquid molecules at the surface, which causes the liquid to behave as if it has an elastic 'skin.' In the case of water, this property allows it to resist external forces, enabling it to form a convex meniscus when poured carefully into a glass, allowing the water to rise slightly above the rim without spilling.

Cohesion and Adhesion

Cohesion refers to the attraction between molecules of the same substance, while adhesion is the attraction between different substances. In water, cohesive forces allow the molecules to stick together, while adhesive forces help them cling to the glass. This combination allows water to be 'stacked' above the rim of the glass due to the balance of these forces.

Capillary Action

Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces. This phenomenon occurs due to the interplay of cohesive and adhesive forces. When water is poured carefully, it can rise slightly above the rim of the glass due to capillary action, as the adhesive forces between the water and the glass surface help pull the water upward.