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Types of Chemical Reactions. Types of Chemical Reactions. Synthesis Two or more substances form one new substance A + B AB H 2 + O 2 H 2 O N 2 + H 2 NH 3. Types of Chem Rxns – cont’d. Decomposition One substance breaks down to form two or more new substances AB A + B
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Types of Chemical Reactions • Synthesis • Two or more substances form one new substance • A + B AB H2 + O2 H2O N2 + H2 NH3
Types of Chem Rxns – cont’d • Decomposition • One substance breaks down to form two or more new substances • AB A + B PbCO3 PbO + CO2 H2CO3 H2O + CO2
Types of Chem Rxns – cont’d • Single Displacement • One substance replaces another in a compound • A + BC B + AC Li + AlCl3 LiCl + Al
Types of Chem Rxns – cont’d • Double Displacement • Two substances “swap partners” in two compounds • AB + CD AD + CB KOH + HBr KBr + H2O NaOH + H2CO3 Na2CO3 + H2O
Types of Chem Rxns – cont’d • Neutralization [Acid / Base] • Double-displacement reaction where an acid and a base form a chemical “salt” and water KOH + HBr KBr + H2O NaOH + H2CO3 Na2CO3 + H2O
Review – Acids & Bases • Acids - General Characteristics • Taste Sour • Have a pH of less than 7 • Produce Hydronium H3O+1 in solution • Have an “extra” H- on the beginning of the formula H2SO4 – (Hydro)Sulfuric Acid H3PO4 – (Hydro)Phosphoric Acid HNO3 – (Hydro)Nitric Acid HCl – Hydrochloric Acid
Review – Acids & Bases • Bases - General Characteristics • Taste bitter • Have a pH of more than 7 • Produce Hydroxide OH–1 in solution • Have an –OH on the end of the formula NaOH – Sodium Hydroxide KOH – Potassium Hydroxide Ca(OH)2 – Calcium Hydroxide NH4OH– Ammonium Hydroxide
Types of Chem Rxns – cont’d • Combustion • Carbon compound combusts with oxygen gas to form carbon dioxide and water CH4 + O2 CO2 + H2O C2H6 + O2 CO2 + H2O
Discuss • In which two types of reactions do you find water as a product? • ---------------------------------- • On-Level – on page 6 [Chembalancer w/s], complete the “type of reaction” for #s 1-11. • Honors – check your answers to Chembalancer “type of reaction” pages mid6-top8.
Chembalancer Activity Answers 1-11 1. synthesis 7. combustion 2. synthesis 8. double displacement 3. synthesis 9. synthesis 4. synthesis 10. synthesis 5. decomposition 11. decomposition 6. single displacement
Activation Energy • Some reactions require a little “jump start” to proceed • Activation Energy • Energy required to be applied to start a reaction • amount of energy from starting point [reactants] to top of reaction curve • Examples • Applying friction to start a match • The match causing a log to burn
Activation Energy – cont’d • Hydrogen + Oxygen Water Activation Energy Hydrogen [gas] Oxygen [gas] Water [liquid]
Changes in Energy • Every reaction has a change in energy • Endothermic – absorbs energy from the environment to complete reaction • Feels “COLD” to its surroundings • Products have MORE energy than the reactants
Changes in Energy – cont’d • Endothermic vs. Endergonic • Endothermic requires heat • Endergonic requires energy
Changes in Energy – cont’d • Every reaction has a change in energy • Exothermic – releases energy to the environment as the reaction proceeds • Feels “HOT” to its surroundings • Products have LESS energy than reactants
Changes in Energy – cont’d • Exothermic vs. Exergonic • Exothermic gives off heat • Exoergonic gives off energy ~End~
Homework • complete worksheets: • Types of Chemical Reactions [pg10 - top11] • Classifying Chemical Reactions [pg 11]