5 Signs of a Chemical Reaction 1. 2. 3. 4. 5. Color change Increase or decrease in temperature Gas production (not boiling) Precipitation: 2 liquids react to make a solid Change in properties (density, smell, taste, texture, melting points, boiling points, hardness, etc.) Did a chemical reaction take place? Write a paragraph on the other side of the paper that answers the above question. Be sure to: 1. Write a topic sentence. 2. Have at least 4 concrete detailed sentences. 3. Those 4 sentences should clearly state which signs of a chemical reaction were present and describe what happened. 4. Write a closing sentence. You are to quietly write this by yourself without talking. Yes a chemical reaction did take place! We know because: 1. The properties changed: It got a lot larger. 2. The temperature changed. The temperature rose, the cup got warmer. 3. A gas was produced. You could seem the small bubbles forming everywhere. 4. A precipitate formed. 2 liquids changed to a solid. A chemical reaction took place when the 2 chemicals were mixed because 4 signs of a chemical reaction were observed. The properties of the chemicals changed. They started out very small and grew to something very large. The reaction was exothermic. Heat was released and the cup got warmer. Gas was produced during the chemical reaction. Little bubbles formed throughout the mixture. A precipitate formed. The starting chemicals were liquids, the product was a solid. Properties changing, heat being released, gas production, and a precipitate prove that a chemical reaction did take place.