Free Endothermic and Exothermic Reaction Worksheets PDF - Free Printable

Solution to the "Exo & Endo Energy" Worksheet

This worksheet asks you to explain the energy changes in exothermic and endothermic chemical reactions using the provided images and to draw the direction of arrows (indicating energy flow) in each case.

---

🔹 1. Exothermic Reaction

Image: A flame (fire)

#### ✔ Explanation:
An exothermic reaction is a chemical reaction that releases energy (usually as heat) into the surroundings. The products have less energy than the reactants, so the excess energy is released.

- Energy Flow: Energy flows from the system (reaction) to the surroundings.
- Example: Combustion of fuel (like wood or gasoline), where heat and light are given off.

#### 📌 Arrow Direction:
Draw an arrow pointing outward from the reaction (e.g., from the flame toward the outside).
👉 This shows energy being released.

> Label: "Energy released"

---

🔹 2. Endothermic Reaction

Image: Ice cubes melting

#### ✔ Explanation:
An endothermic reaction is a chemical reaction that absorbs energy from the surroundings. The products have more energy than the reactants, so energy must be taken in.

- Energy Flow: Energy flows from the surroundings into the system (reaction).
- Example: Melting ice, photosynthesis, or dissolving some salts in water.

#### 📌 Arrow Direction:
Draw an arrow pointing inward toward the reaction (e.g., from the surrounding air or environment into the ice cubes).
👉 This shows energy being absorbed.

> Label: "Energy absorbed"

---

✔ Summary Table:

| Reaction Type | Energy Change | Energy Flow Direction | Example |
|-------------------|----------------------------|------------------------------|-----------------------------|
| Exothermic | Releases energy | System → Surroundings | Burning wood, fire |
| Endothermic | Absorbs energy | Surroundings → System | Melting ice, photosynthesis |

---

✏️ How to Fill Out the Worksheet:

1. Exothermic Reaction Box:
- Write: *"In an exothermic reaction, energy is released into the surroundings. The products have less energy than the reactants."*
- Draw an arrow pointing outward from the flame.

2. Endothermic Reaction Box:
- Write: *"In an endothermic reaction, energy is absorbed from the surroundings. The products have more energy than the reactants."*
- Draw an arrow pointing inward toward the ice cubes.

---

💡 Tip:

Think of it like this:
- Exo = "out" (like "exit") → energy goes out.
- Endo = "in" (like "enter") → energy comes in.

---

✔ Final Answer:
- Exothermic: Energy released → arrow points outward.
- Endothermic: Energy absorbed → arrow points inward.

You’ve now completed the worksheet with correct explanations and arrow directions!