Explanation: In this demonstration, we will be observing a chemical reaction between vinegar (acetic acid) and baking soda (sodium bicarbonate). When these two substances are combined, they react to produce carbon dioxide gas, which causes bubbling and fizzing.

Key principles: This demonstration illustrates the concept of a chemical reaction, where two or more substances combine to form a new substance with different properties. It also demonstrates the production of a gas as a byproduct of the reaction.

Safety precautions: Ensure that the demonstration is conducted in a well-ventilated area to prevent the buildup of carbon dioxide gas. Wear safety goggles to protect your eyes from any splashes. Avoid inhaling the gas produced during the reaction.

Materials needed: - Vinegar (acetic acid) - Baking soda (sodium bicarbonate) - Measuring spoons - Clear plastic cup - Stirring rod

Step-by-step guide: 1. Measure out 1 tablespoon of baking soda and place it in the clear plastic cup. 2. Slowly pour 1/4 cup of vinegar into the cup with the baking soda. 3. Observe the reaction as the two substances combine. You should see bubbling and fizzing as carbon dioxide gas is produced. 4. Use the stirring rod to mix the two substances together and enhance the reaction. 5. Discuss the observations with the students and explain the chemical reaction that took place. 6. Dispose of the mixture properly after the demonstration is complete.

By following these steps and emphasizing safety precautions, you can conduct a simple and safe chemical reaction demonstration for high school students to help them understand the concept of chemical reactions and the factors that influence reaction rates.