Hamilton/Rathburn Chemistry Chemical Reactions Hamilton/Rathburn Chemistry

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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