1. Topic: Chemical Reactions and Equations PSSA: 3.4.7.A/S8.C.1.1

2. Objective: TLW identify the reactants and products in a chemical reaction, determine the type of reaction that is occurring, and balance the chemical equation.

3. MI #1: What is a Chemical Reaction? A chemical reaction is a process by which one or more substances change to produce one or more new substances. Chemical reactions involve chemical changes – new substances are formed. Chemical bonds are formed and/or broken during the reaction.

4. MI #2: Signs of Chemical Reactions Precipitates – solids formed in a solution Gas Formation (Bubbles) Color Changes Energy Change – energy is released (as heat or light) or energy is taken into the new substances

5. MI #3: Chemical Formulas Chemical formulas are combinations of chemical symbols and numbers used to represent a substance (ex – H 2 O) Subscripts are numbers placed to the lower right of a chemical symbol to indicate how many atoms of that element are in one molecule of that compound. (ex – H 2 SO 4 ) No subscript indicates that there is one atom of that element in the compound.

6. MI #4: Chemical Equations A chemical equation is a representation of a chemical reaction using symbols and formulas to show the relationship between the reactants and the products. Reactants are substances that participate in a chemical reaction, while products are produced during the reaction.

7. MI #5: The Law of Conservation of Mass The Law of Conservation of Mass states that matter cannot be created or destroyed during ordinary physical and chemical changes. This means that during a chemical reaction, the number of atoms of each element of each reactant must be equal to the number of atoms of each element in each product.

8. MI #6: Balancing Chemical Equations A coefficient is a number placed in front of a chemical symbol or formula that indicates how many molecules of that substance are required for the reaction. H 2 + O 2 H 2 O 2H 2 + O 2 2H 2 O To Balance a Chemical Equation….. –Count the number of atoms of each element on both sides of the equation. –Place coefficients in front of formulas to balance atoms. –Check your work

9. So What…? Real Life Application Balancing chemical equations allows us to understand the Law of Conservation of Mass and to practice reasoning skills that will benefit us throughout our lives.