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 reaction is 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.
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10. Replacement Reactions (cont.)
Halogens frequently replace other halogens in replacement reactions.
Halogens also have different reactivities and do not always replace each other.
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11. Replacement Reactions (cont.)
Double replacement reactions occur 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.
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13. Replacement Reactions (cont.)
This table shows the steps to write double replacement reactions.
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14. Replacement Reactions (cont.)
This table summarizes different ways to predict the products of a chemical reaction.
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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 A B C D
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 A B C D
Section 9-2