Chemical Reactions Cornell Notes page 139
Chemical Properties Characteristics of a material that can only be determined during a Chemical Reaction Reactivity Flammability pH Oxidation
Chemical Reaction Reactants Products The process of substances changing into new substances. Substances at start of reaction that are changed New substances made from the reaction (end results).
The Law of Conservation of Matter Matter is not created or destroyed. mass of reactants should equal mass of products!
4 Signs of a Chemical Reaction Used to identify when a reaction has occurred Not definite- more signs increase confidence that a reaction has occurred. Best indicator is that substances have new properties.
4 Signs of a Chemical Reaction 1. Formation of a Gas Bubbles Least reliable sign Ex.) baking soda and vinegar; yeast and hydrogen peroxide.
4 Signs of a Chemical Reaction 2. Formation of a Precipitate Solid is created when two liquids are mixed May look like small particles suspended in a liquid.
4 Signs of a Chemical Reaction 3. Unexpected Color Change When two substances are mixed and an unexpected color occurs. Ex.) Bleach spilt on colored clothes.
4 Signs of a Chemical Reaction 4. Temperature Change temperature changes as energy is used or released from the reaction. Exothermic- heat is released (gets warmer) Endothermic- heat is absorbed (gets colder)
What is a Catalyst? A substance that starts or speeds up a chemical reaction that is not used or changed in the reaction. lowers the amount of energy needed in a chemical reaction
Oxidation Reactions • Specific type of Chemical Reaction in which a substance reacts with oxygen • Often results in a color change • Apples turn brown • Many metals oxidize, such as iron turning red or copper turning green; we often call this rust.
Oxygen reacts with iron to create rust. • The new color is evidence that a chemical reaction has taken place.
Oxygen reacts with apples to cause them to brown • Adding citric acid prevents the oxidation reaction.
Oxygen reacts with copper to create a green color called verdigris • Many oxidation reactions take time to happen.
Burning is an example of a rapid oxidation reaction. • Oxygen is required for burning, the heat and light are evidence that a reaction is taking place.