Section 9-2

2. Section 9.2 Classifying Chemical Reactions • Classify chemical reactions. metal: an element that is a solid at room temperature, a good conductor of heat and electricity, and is generally shiny • Identify the characteristics of different classes of chemical reactions. Section 9-2

3. Section 9.2 Classifying Chemical Reactions (cont.) synthesis reaction combustion reaction decomposition reaction single-replacement reaction double-replacement reaction precipitate There are four types of chemical reactions: synthesis, combustion, decomposition, and replacement reactions. Section 9-2

4. Types of Chemical Reactions • Chemists classify reactions in order to organize the many types. • A synthesis reaction is a reaction in which two or more substances react to produce a single product. Section 9-2

5. Types of Chemical Reactions (cont.) • When two elements react, the reaction is always a synthesis reaction. Section 9-2

6. Types of Chemical Reactions (cont.) • In a combustion reaction, oxygen combines with a substance and releases energy in the form of heat and light. • Heated hydrogen reacts with oxygen to produce heat and water in a combustion reaction. This is also a synthesis reaction. Section 9-2

7. Decomposition Reactions • A decomposition reactionis one in which a single compound breaks down into two or more elements or new compounds. • Decomposition reactions often require an energy source, such as heat, light, or electricity, to occur. Section 9-2

8. Replacement Reactions • A reaction in which the atoms of one element replace the atoms of another element in a compound is called a single replacement reaction. A + BX → AX + B Section 9-2

9. Replacement Reactions (cont.) • A metal will not always replace a metal in a compound dissolved in water because of differing reactivities. • An activity series can be used to predict if reactions will occur. Section 9-2

10. Replacement Reactions (cont.) • Halogens frequently replace other halogens in replacement reactions. • Halogens also have different reactivities and do not always replace each other. Section 9-2

11. Replacement Reactions (cont.) • Double replacement reactionsoccur when ions exchange between two compounds. • This figure shows a generic double replacement equation. Section 9-2

12. Replacement Reactions (cont.) • The solid product produced during a chemical reaction in a solution is called a precipitate. • All double replacement reactions produce either water, a precipitate, or a gas. Section 9-2

13. Replacement Reactions (cont.) • This table shows the steps to write double replacement reactions. Section 9-2

14. Replacement Reactions (cont.) • This table summarizes different ways to predict the products of a chemical reaction. Section 9-2

15. A B C D Section 9.2 Assessment Which of the following is NOT one of the four types of reactions? A.deconstructive B.synthesis C.single replacement D.double replacement Section 9-2

16. A B C D Section 9.2 Assessment The following equation is what type of reaction? KCN(aq) + HBr(aq) → KBr(aq) + HCN(g) A.deconstructive B.synthesis C.single replacement D.double replacement Section 9-2