Properties of Water Worksheet KEY | PDF | Properties Of Water | Water - Free Printable

The worksheet you've provided is a "Properties of Water Worksheet" that tests understanding of the physical and chemical properties of water. Below is a detailed explanation of each answer, along with reasoning to help reinforce the concepts.

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1. The hydrogen and oxygen atoms are held together by ________ bonds.

✔ Answer: *Covalent*
🔹 Explanation: In a water molecule (H₂O), hydrogen and oxygen share electrons through covalent bonds. Each hydrogen atom shares one electron with the oxygen atom, forming two covalent bonds.

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2. The electrons are not shared equally creating a ________ molecule.

✔ Answer: *Polar*
🔹 Explanation: Oxygen is more electronegative than hydrogen, so it pulls the shared electrons closer to itself. This unequal sharing creates a polar molecule, with a partial negative charge on oxygen and partial positive charges on hydrogens.

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3. The polarity of water allows it to ________ most substances. Because of this, it is referred to as the ________ solvent.

✔ Answers: *Dissolve*, *Universal*
🔹 Explanation: Water's polarity enables it to surround and dissolve many ionic and polar substances. This makes it the universal solvent, essential for biological processes.

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4. Water molecules stick to other water molecules. This property is called ________.

✔ Answer: *Cohesion*
🔹 Explanation: Cohesion is the attraction between like molecules. Water molecules form hydrogen bonds with each other, leading to strong cohesion—this helps in capillary action and transport in plants.

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5. Hydrogen bonds form between adjacent water molecules because the ________ charged hydrogen end of one water molecule attracts the ________ charged oxygen end of another water molecule.

✔ Answers: *Positively*, *Negatively*
🔹 Explanation: Due to polarity, hydrogen atoms carry a partial positive charge and oxygen carries a partial negative charge. These opposite charges attract, forming hydrogen bonds between water molecules.

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6. Water molecules stick to other materials due to its polar nature. This property is called ________.

✔ Answer: *Adhesion*
🔹 Explanation: Adhesion is the attraction between different substances. Water adheres to surfaces like glass or plant cell walls due to its polarity, aiding in movement up stems via capillary action.

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7. ________ ________ creates the skin-like surface formed due to the polar nature of water.

✔ Answer: *Surface tension*
🔹 Explanation: Surface tension results from cohesive forces at the surface of water. Molecules at the surface experience inward pull, creating a "skin" that allows small insects to walk on water.

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8. ________ is the tendency for fluids to resist flow. ________ water is more viscous than warmer water, allowing floating organisms to use less energy to keep from sinking.

✔ Answers: *Viscosity*, *Cooler*
🔹 Explanation: Viscosity measures resistance to flow. Cooler water has stronger hydrogen bonding, making it more viscous. This helps aquatic organisms float more easily.

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9. ________ is when water changes from a gas to a liquid.

✔ Answer: *Condensation*
🔹 Explanation: Condensation occurs when water vapor loses heat and turns into liquid droplets (e.g., dew forming on grass).

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10. ________ is when water changes from a solid directly to a gas.

✔ Answer: *Sublimation*
🔹 Explanation: Sublimation is the phase change from solid to gas without becoming liquid first. Example: dry ice (solid CO₂) sublimes, or frost turning into vapor.

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11. ________ is when water changes from a gas directly to a solid.

✔ Answer: *Deposition*
🔹 Explanation: Deposition is the reverse of sublimation—water vapor turns directly into ice (e.g., frost forming on cold surfaces).

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12. Why does ice float?

✔ Answer: *Water is less dense in solid form because hydrogen bonding between water molecules pushes molecules further apart into a set crystalline pattern.*
🔹 Explanation: When water freezes, hydrogen bonds form a hexagonal lattice that spaces molecules farther apart than in liquid water. This lower density causes ice to float, insulating lakes and oceans.

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13. List the properties that ocean water has due to the fact that it contains salt.

✔ Answers:
- Higher density
- Conductivity
- Decreased surface tension

🔹 Explanation:
- Higher density: Dissolved salts increase mass per unit volume.
- Conductivity: Ions (like Na⁺ and Cl⁻) allow ocean water to conduct electricity.
- Decreased surface tension: Salts disrupt hydrogen bonding slightly, reducing surface tension compared to pure water.

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✔ Summary of Key Concepts:

| Property | Description |
|--------|-------------|
| Polarity | Unequal electron sharing → partial charges |
| Hydrogen Bonding | Attraction between H⁺ and O⁻ of adjacent molecules |
| Cohesion & Adhesion | Stickiness within and between molecules |
| Surface Tension | Skin-like surface due to cohesion |
| Viscosity | Resistance to flow; higher in cooler water |
| Phase Changes | Evaporation, condensation, sublimation, deposition |
| Density Anomaly | Ice floats because it’s less dense than liquid water |
| Salinity Effects | Increases density, conductivity; decreases surface tension |

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This worksheet effectively covers why water is essential for life—its unique properties support biological systems, weather patterns, and ecosystems. Let me know if you'd like a printable version or study guide!