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Chapter 10. Chemical Reactions. Section 10.1. Reactions and Equations. Section 10.1 Objectives. Recognize evidence of chemical change Represent chemical reactions with equations. Chemical reaction Reactant Product . Chemical equations coefficient. Key Terms. Chemical Reactions.
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Chapter 10 Chemical Reactions
Section 10.1 Reactions and Equations
Section 10.1 Objectives • Recognize evidence of chemical change • Represent chemical reactions with equations
Chemical reaction Reactant Product Chemical equations coefficient Key Terms
Chemical Reactions • Atoms of one or more substances are rearranged to form different substances • Another name= chemical change • Important part of everyday life
Evidence of a Reaction • How to tell if a chemical reaction has taken place • Temperature change • Color change • Odor • Gas bubbles
Representing Chemical Reactions • Reactants: the starting substances • Products: resulting or ending substances • Arrow: “react to produce” or “yield” • Reactant 1 + reactant 2 product 1 + product 2
Symbols used in Equations • Table 10.1 on page 278 • Why do these symbols mean? • (g) • • (s) • (aq) • + • (l)
Physical States • Must know the state of reactant and products in order to determine if reaction will occur
Types of Equations • Three types of equations • Word • Skeleton • Chemical
Word Equations • Used to indicate the reactants and products of chemical reactions • Uses the actual names of the substances involved • Setup: Reactant 1 + Reactant 2 Product 1 Ex: Iron(s) + Chlorine(g) Iron(III) Chloride(s)
Skeleton Equations • Uses chemical formulas to represent the substances unlike the word equation • Chemical formulas take the place of the words • Iron(s) + Chlorine(g) Iron(III) Chloride(s) would become: Fe(s) + Cl2(g) Fe Cl3(s)
Practice Problems • Page 279
Chemical Equations • Uses chemical formulas like the skeleton • Shows matter is conserved during a reaction (Law of Conservation of Mass) • Uses identities and relative amounts of the substances involved in a chemical reaction • Everything is balanced in a chemical equation
Balancing Chemical Equations • Find correct coefficients for chemical formulas • Coefficient is usually a whole number • 1 is understood- not written
Steps to Balance a Chemical Equation • 1: Write the skeleton equation • 2: Count the atoms of elements in the reactants • 3: Count the atoms of elements in the products • 4:Change the coefficients to make both sides of the equation the equal • 5:Write the coefficient(s) in the lowest ratio possible • 6:Check your work • Ex: 2H2(g) + O2(g) 2H2O(g)
Practice Problems • Page 282
Homework • 7-13 on page 283