Water adhesion is the tendency of water molecules to stick to other substances due to their polar nature.
Here's a breakdown:
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Definition: Adhesion, in the context of water, refers to the attractive forces between water molecules and different substances. It's essentially water "sticking" to something else.
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Polarity: Water molecules (H₂O) are polar, meaning they have a slightly positive end (hydrogen atoms) and a slightly negative end (oxygen atom). This polarity arises from the unequal sharing of electrons in the covalent bonds between oxygen and hydrogen.
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How it Works: The slightly positive end of a water molecule is attracted to negatively charged or polar regions of other substances. Conversely, the slightly negative end of a water molecule is attracted to positively charged or polar regions.
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Examples:
- Water droplets clinging to a spiderweb: The polar water molecules are attracted to the polar or charged regions on the silk of the web.
- Water moving up a narrow tube (capillary action): Adhesion to the walls of the tube, combined with cohesion (water molecules sticking to each other), allows water to defy gravity and move upwards. This is crucial for water transport in plants.
- Meniscus formation in a graduated cylinder: The curve of water in a glass cylinder is due to water adhering to the glass walls.
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Importance: Adhesion is vital for numerous natural processes, including:
- Plant life: It contributes to capillary action, enabling plants to draw water from the soil up to their leaves.
- Surface tension: Adhesion, alongside cohesion, contributes to surface tension, allowing insects to walk on water.
- Weathering: Adhesion plays a role in the weathering of rocks and minerals.
In summary, water adhesion is the attractive force between water molecules and other substances, driven by water's polar nature and essential for many biological and physical processes.
