To see how endothermic and exothermic reactions work, you can try these easy experiments:

Exothermic Reactions

1. Calcium Chloride and Water

   • What You Need: Calcium chloride (CaCl₂), water, thermometer, disposable cup.
   • Steps:
     1. Pour 50 mL of water into a disposable cup.
     2. Check and write down the starting temperature (like 23°C).
     3. Add 5 grams of calcium chloride and stir it well.
   • What to Watch For: The temperature of the liquid will go up, often past 30°C. This shows that heat is being released, which is an exothermic reaction.

2. Vinegar and Baking Soda

   • What You Need: Vinegar (which is acetic acid), baking soda (sodium bicarbonate), thermometer, balloon.
   • Steps:
     1. Pour 50 mL of vinegar into a flask.
     2. Add 5 grams of baking soda.
     3. Quickly put a balloon over the opening of the flask to catch the gas that forms.
   • What to Watch For: The balloon will blow up, and the temperature will go down. This shows an endothermic reaction happening when the baking soda mixes with the vinegar.

Endothermic Reactions

1. Ammonium Nitrate and Water
   • What You Need: Ammonium nitrate (NH₄NO₃), water, thermometer, disposable cup.
   • Steps:
     1. Mix 10 grams of ammonium nitrate in 50 mL of water.
     2. Measure and write down the starting temperature (like 25°C).
     3. Stir and watch the temperature drop, sometimes down to about 15°C.
   • What to Learn: This reaction takes in heat from the surroundings, showing that it is an endothermic process.

Conclusion

These experiments let you see how energy changes in chemical reactions. They help you understand the differences between exothermic reactions (which release heat) and endothermic reactions (which absorb heat) by measuring temperature changes.