SOLUTION: The Properties of Water Based Discussion - Studypool - Free Printable

Let's go through the worksheet and solve each problem, explain the correct answers, and clarify any misconceptions.

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Key Term Definitions (Already Filled In – Let’s Review)

1. Polarity: Uneven distribution of charges across a molecule making one end positive (H) and the other negative (O).
✔ Correct.

2. Cohesion: The tendency for water molecules to form weak bonds and stick to each other.
✔ Correct.

3. Adhesion: The tendency of water to stick to other substances.
✔ Correct.

4. Capillary Action: Both adhesion and cohesion allow water to move in one continuous column from a plant's roots to its leaves. This upward movement is called capillary action.
✔ Correct.

5. Surface Tension: A force that acts on the particles at the surface of a liquid.
✔ Correct.

6. Specific Heat: The amount of heat needed to increase the temperature of 1 kg of a substance by 1°C.
✔ Correct.

7. Hydrogen Bond: The positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules, causing them to stick together like weak magnets. These temporary bonds break easily.
✔ Correct.

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Question 1: Circle the letter of each sentence that is true about water's structure.

a. Water is made up of atoms bonded to form molecules.
✔ True – Water consists of two hydrogen atoms and one oxygen atom covalently bonded to form H₂O molecules.

b. Water contains half as many hydrogen atoms as oxygen atoms.
✘ False – This is backwards. Each water molecule has two hydrogen atoms and one oxygen atom, so there are twice as many hydrogen atoms as oxygen atoms.

c. Water molecules tend to push away from each other.
✘ False – Water molecules attract each other due to hydrogen bonding and cohesion.

d. The chemical formula for water is H₂O.
✔ True – Correct chemical formula.

🔹 Correct Answers: a and d

> ✔ You circled a and d — this is correct.

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Question 2: One side of the water molecule has a positive charge, while the other side has a negative charge. What do the charges indicate?

Options:
a. Water is a polar molecule.
b. Water is a nonpolar molecule.
c. Water is an ionic compound.
d. Water is an ion.

✔ Answer: a. Water is a polar molecule.

Explanation:
- Due to the uneven sharing of electrons (oxygen is more electronegative), the oxygen end becomes partially negative and the hydrogen ends become partially positive.
- This creates a dipole, meaning the molecule has a positive and negative end → polar molecule.
- It is not ionic (no transfer of electrons), nor is it an ion (it’s a neutral molecule).
- So, a is correct.

> ✔ You circled a — this is correct.

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Question 3: Bonds that form between water molecules are called ________ bonds.

✔ Answer: Hydrogen bonds

Wait — you wrote "covalent".

⚠️ Mistake here!

- Covalent bonds are the strong bonds within a water molecule (between H and O atoms).
- The bonds between water molecules are hydrogen bonds — weaker interactions between the H of one molecule and the O of another.

🔹 Correct Answer: hydrogen bonds

> ✘ You wrote "covalent" — this is incorrect.
> ✔ Should be: hydrogen bonds

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Question 4: True or False? Hydrogen bonds are strong and require a lot of energy to break.

✔ Answer: False

Explanation:
- Hydrogen bonds are relatively weak compared to covalent bonds.
- They break and reform easily — which allows water to flow and change state.
- However, collectively, they are strong enough to give water high boiling point, surface tension, etc.

> ✔ You circled False — this is correct.

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Question 5: The tendency for water molecules to stick to other water molecules is called ________.

✔ Answer: Cohesion

You filled in: cohesion — ✔ Correct

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Question 6: A force that acts on the particles of a liquid at the surface is called ________.

✔ Answer: Surface tension

You filled in: surface tension — ✔ Correct

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Question 7: How does surface tension force the surface of water to curve?

Your answer: *"the force acts the particles"* — incomplete and unclear.

✔ Better Answer:

> Surface tension causes water molecules at the surface to be pulled inward by cohesive forces from neighboring molecules below. This creates a "skin-like" effect, minimizing surface area. When water is in a container or near a solid object, this inward pull can cause the surface to curve (e.g., meniscus formation).

More specifically:
- In a narrow tube, adhesion to the sides and cohesion among water molecules cause the water to climb up and form a curved surface (meniscus).
- For example, water forms a concave meniscus in glass because adhesion > cohesion.

🔹 Improved Answer:
> Surface tension results from cohesive forces pulling surface water molecules inward. This causes the surface to behave like a stretched elastic membrane, leading to curvature such as a meniscus when water interacts with containers.

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✔ Final Summary of Corrections:

| Question | Your Answer | Correct Answer | Feedback |
|--------|-------------|----------------|--------|
| 1 | a, d | a, d | ✔ Correct |
| 2 | a | a | ✔ Correct |
| 3 | covalent | hydrogen bonds | ✘ Incorrect — fix this |
| 4 | False | False | ✔ Correct |
| 5 | cohesion | cohesion | ✔ Correct |
| 6 | surface tension | surface tension | ✔ Correct |
| 7 | "the force acts the particles" | See explanation above | ✘ Incomplete — improve |

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📝 Final Answer Key (Corrected):

3. Bonds that form between water molecules are called hydrogen bonds.

7. Surface tension causes the surface of water to curve because the cohesive forces between water molecules pull the surface molecules inward, minimizing surface area. This leads to a curved shape, such as a meniscus, especially in narrow tubes or when interacting with surfaces.

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