1. Hamilton/Rathburn Chemistry
Chemical Reactions
Hamilton/Rathburn Chemistry

2. Chemical Reactions Parts of a chemical reaction:
Reactants – substances before reaction occurs
Products – substances produced by the reaction

3. Chemical Reactions Reason why reactions occur:
Increase in stability for products

4. Types of Reactions
Combination - two substances combine to form new substance
A + B  AB
Ca + Cl2  CaCl2

5. Types of Reactions Combustion – substance reacts with oxygen
A + O2  AO
CH4 + O2  CO2 + H2O

6. Types of Reactions
Decomposition – substance breaks into two or more substances
AB  A + B
MnSO4  MnO + SO3

7. Types of Reactions
Single-replacement – uncombined element “trades places” with an element in a compound
A +BX  AX + B
Cd + 2 HCl  CdCl2 + H2

8. Types of Reactions
Double-replacement – two binary compounds “trade partners”
AX +BY  AY + BX
CaCO3 + 2 HCl 
CaCl2 + H2CO3

9. Types of Reactions
Combination - two substances combine to form new substance
A + B  AB
Ca + Cl2  CaCl2

10. Types of Reactions Combustion – substance reacts with oxygen
A + O2  AO
CH4 + O2  CO2 + H2O

11. Types of Reactions
Decomposition – substance breaks into two or more substances
AB  A + B
MnSO4  MnO + SO3

12. Types of Reactions
Single-replacement – uncombined element “trades places” with an element in a compound
A +BX  AX + B
Cd + 2 HCl  CdCl2 + H2

13. Types of Reactions
Double-replacement – two binary compounds “trade partners”
AX +BY  AY + BX
CaCO3 + 2 HCl 
CaCl2 + H2CO3

14. Chemical Equations Diatomic molecule reminder… Hydrogen H2 Nitrogen N2
Oxygen O2
Fluorine F2
Chlorine Cl2
Bromine Br2
Iodine I2

15. Chemical Equations Can include heat
Endothermic – heat, from surroundings, enters the system, has positive heat of reaction (DH) value, reactants have lower potential energy than products

16. Chemical Equations
Can include heat
Endothermic – heat, from surroundings, enters the system
Exothermic – heat exits the system and goes to surroundings, has negative heat of reaction (DH) value , reactants have higher potential energy than products