This educational worksheet breaks down the properties of solids, liquids, and gases alongside practice problems for identifying phase changes.

You're absolutely right — there are errors in the answers provided on this worksheet. Let’s go through each one carefully and correct them with clear explanations.

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## 🔍 Understanding Phase Changes & Energy

Before we fix the worksheet, let’s review:

- Energy INCREASES → particles move faster → matter becomes *less ordered* (solid → liquid → gas)
- Energy DECREASES → particles slow down → matter becomes *more ordered* (gas → liquid → solid)

Phase changes that require energy input (endothermic):
- Melting (solid → liquid)
- Vaporization/Boiling (liquid → gas)
- Sublimation (solid → gas)

Phase changes that release energy (exothermic):
- Freezing (liquid → solid)
- Condensation (gas → liquid)
- Deposition (gas → solid)

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## ✔ Correcting Each Problem

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1) Left box: particles spread out (liquid) → Right box: particles tightly packed (solid)

➡️ This is Freezing (liquid → solid) — CORRECT

But energy?
→ To freeze, you must remove energy (cool it down).
✔ So energy DECREASES

🔴 ERROR: The worksheet says “Increase” — that’s wrong.
✔️ Correction: Circle “decrease”

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2) Left box: particles far apart (gas) → Right box: particles closer (liquid)

➡️ This is Condensation (gas → liquid) — CORRECT

Energy?
→ To condense gas into liquid, you must remove energy (cool it).
✔ So energy DECREASES

🔴 ERROR: Worksheet says “Increase” — wrong again.
✔️ Correction: Circle “decrease”

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3) Left box: particles tightly packed (solid) → Right box: particles looser (liquid)

➡️ This is Melting (solid → liquid) — CORRECT

Energy?
→ To melt a solid, you must add energy (heat it up).
✔ So energy INCREASES

🟢 CORRECT: Worksheet says “Increase” — this one is right!

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## ✍️ Final Corrected Answers:

| # | Phase Change | Energy Change |
|---|----------------|---------------|
| 1 | Freezing | Decrease |
| 2 | Condensation | Decrease |
| 3 | Melting | Increase |

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## 🧠 Why This Matters

Understanding whether energy increases or decreases during phase changes is crucial for grasping how heat transfer affects matter. For example:
- When water freezes, it releases heat into the environment.
- When ice melts, it absorbs heat from its surroundings.

This is why adding salt to ice lowers its melting point — it requires more energy (from the environment) to melt, which cools things down.

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## ✔ Summary of Corrections

- Problem 1: Energy → decrease (not increase)
- Problem 2: Energy → decrease (not increase)
- Problem 3: Energy → increase ✔ (already correct)

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Let me know if you’d like a diagram or mnemonic to remember these! 😊