Chemical Reactions Chemical Reactions n Produce new substances

Chemical Reactions

Chemical Reactions n Produce new substances by changing the way in which atoms are arranged. REACTANTS= substances used in a chemical reaction PRODUCTS= substances formed by chemical reaction

Sign #1 n n Reactants: Cabbage Juice and Vinegar; Cabbage Juice and Baking Soda Add 10 m. L of cabbage juice to 2 test tubes Add a few drops of vinegar to one test tube Add one lab scoop of baking soda to another

6 Signs of a Chemical Reaction! COLOR CHANGE n n n Substances change color Color change is a product of two or more reactants Examples: Rust, leaves changing color, mold

Sign #2 n n Reactants: Baking Soda and Vinegar (Acetic Acid) 10 m. L of Vinegar in test tube 1 lab scoop of baking soda Swirl and observe!

6 Signs of a Chemical Reaction! FORMATION OF A GAS n n Bubbles often appear Fizzes A product gas is leaving the reaction mixture Examples: vinegar + baking soda = carbon dioxide

Sign #3 n n n Reactants: Citric Acid and Baking Soda 10 m. L Citric acid in test tube Take temperature Combine w/ 1 lab scoop of baking soda Swirl and observe temperature!

6 Signs of a Chemical Reaction! ENDOTHERMIC REACTION (temperature/energy change) n n Chemical bonds break Energy (heat) is absorbed from surroundings Substance seems cooler Examples: cold packs, photosynthesis

Sign #4 n n n Reactants: Hydrogen Peroxide and Yeast 10 m. L Hydrogen Peroxide in test tube Take temperature Combine w/ 1 lab scoop of yeast Swirl and observe temperature!

6 Signs of a Chemical Reaction! EXOTHERMIC REACTION (temperature/energy change) n n Chemical bonds are made Energy (heat) is released to surroundings Substance seems warmer Examples: fireworks, explosions, hand warmers

Sign #5 n n Reactants: Ammonia and dissolved Epsom Salt 40 m. L ammonia 1 tsp epsom salt dissolved in 40 m. L hot water Combine and observe!

6 Signs of a Chemical Reaction! A PRECIPITATE IS FORMED n n n A solid that forms when two liquids combine The solid particles are the product Examples: Kidney stones, pearls, cheese

6 Signs of a Chemical Reaction! ODOR Produces new smells as the reaction occurs n Examples: Rotting, bad breath n