Unit 5: Chemical Reactions Section 1: Describing Reactions Chemical Reaction Law of Conservation of Mass Chemical Equations and Balancing

A. Physical and Chemical Changes During a physical change, some properties of a material change, but the composition of the material does not change. Examples of physical changes: Grinding Cutting Folding Cracking Filing Bending Phase changes (melting, boiling, condensing, etc)

A. Physical and Chemical changes A change that involves one or more substances turning into new substances is called a chemical change. Examples of chemical changes: decomposing rusting exploding burning oxidizing tarnishing fermenting

PA. Physical and Chemical Changesand Chemical Changes A magnet separates iron from sulfur. This is an example of a physical change. A mixture of iron filings and sulfur can be changed. a) A magnet separates the iron from the sulfur. b) Heat combines iron and sulfur in a compound. Classifying Which change is a chemical change? Explain.

PhA. Physical and Chemical Changesand al and Chemical Changes A mixture of iron and sulfur is heated. The iron and sulfur react and form iron sulfide. This is an example of a chemical change. A mixture of iron filings and sulfur can be changed. a) A magnet separates the iron from the sulfur. b) Heat combines iron and sulfur in a compound. Classifying Which change is a chemical change? Explain.

B. Chemical Reaction Chemical Change: new & different substances formed. 4 Evidences of Chemical Reaction: energy transfer (hot or cool) color change gas formed precipitate formed (solid)

A+B AB B. Chemical Reaction REACTANTS PRODUCTS Chemical Equation: A+B AB yields REACTANTS PRODUCTS present at the start of the rxn produced in the rxn at the end