Examples of Endothermic and Exothermic Reactions with Enthalpy Changes

📚 Quick Study Guide

• 🔥 Exothermic Reactions: Release heat into the surroundings. The enthalpy change ($\Delta H$) is negative ($\Delta H < 0$). Think of burning fuel or explosions!
• ❄️ Endothermic Reactions: Absorb heat from the surroundings. The enthalpy change ($\Delta H$) is positive ($\Delta H > 0$). Examples include melting ice or cooking.
• 🌡️ Enthalpy Change ($\Delta H$): Represents the difference in heat content between products and reactants. $\Delta H = H_{\text{products}} - H_{\text{reactants}}$
• 📝 Key Formulas:
  • Exothermic: Reactants $\rightarrow$ Products + Heat
  • Endothermic: Reactants + Heat $\rightarrow$ Products
• 💡 Tip: Remember 'EXit' for exothermic reactions releasing heat and 'ENter' for endothermic reactions absorbing heat.

🧪 Practice Quiz

1. Which of the following is an example of an exothermic reaction?
   1. Melting ice
   2. Boiling water
   3. Burning wood
   4. Photosynthesis
2. What is the sign of $\Delta H$ for an endothermic reaction?
   1. Positive
   2. Negative
   3. Zero
   4. Undefined
3. Which process absorbs heat from the surroundings?
   1. Combustion
   2. Freezing water
   3. Sublimation of dry ice
   4. Neutralization of an acid and a base
4. In an exothermic reaction, the energy of the products is:
   1. Higher than the reactants
   2. Lower than the reactants
   3. Equal to the reactants
   4. Unrelated to the reactants
5. Which of the following reactions has a negative enthalpy change?
   1. Evaporation
   2. Condensation
   3. Melting
   4. Dissolving ammonium nitrate in water
6. What type of reaction is cooking an egg?
   1. Exothermic
   2. Endothermic
   3. Neither
   4. Both
7. Which of the following is NOT an example of an endothermic reaction?
   1. Chemical ice pack
   2. Ammonium chloride dissolving in water
   3. Rusting of iron
   4. Photosynthesis