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6.1 Types of Chemical Reactions
6 Types of Reactions
• Synthesis (Combination) (3)• Decomposition (3)• Single replacement (4)• Double Replacement (4)• Neutralization (acid-base) (4)• Combustion (4)
Synthesis Reactions
• 2 or more reactants combine to form a single product
• Element + Element Compound• A + B AB
• Ex) 2Na + Cl2 2NaCl
+
Synthesis Reactions-Do not write down-
• Make sure to consider the ion charge of both reactants before forming the product
Mg2+ O2- both have 2- ion charge so they combine as Mg O
• Now balance
• Ex) 2Mg + O2 2MgO
Practice
• Pg 259 #1/2 a,c,e• Check answers- Pg 592
Decomposition Reactions
• Breaking down a compound into smaller compounds or elements
• Reverse of synthesis• Compound Element + Element• AB A + B
• 2NaCl 2Na + Cl2
+
Decomposition Reactions
• Both parts of the compound go back to their element form (no ion charge)
• If they are diatomic, make sure to write the 2
Practice
• Pg 260 #1/2 a,c,• Check answers- Pg 592
Single Replacement Reactions
• An element and a compound react to produce another element and compound
• Element + Compound Element + Compound
• A + BC B + AC• Metals and non-metals go togetherExample: 2Al + 3CuCl2 3Cu +2AlCl3
+ +
Practice
• Pg 261 #1/2 a,c,• Check answers- Pg 592
Double Replacement Reactions
• Two ionic solutions react to form two other ionic solutions
• Ionic solution + Ionic solution Ionic solution + Ionic solid
• AB(aq) + CD(aq) AD(aq) + CB(s)
• Ex) Pb(NO3)2 + 2NaI PbI2 + 2NaNO3
Practice
• Pg 262 #1/2 a,c,• Check answers- Pg 592
Neutralization Reaction
• Been done… check your notes!
++
Combustion Reaction
• Organic compounds react with oxygen to produce carbon dioxide and water
• Ex) CH4 + 2O2 CO2 + 2H20• Ex) C6H12O6 + 6O2 6CO2 + 6H20
++
Practice
• Pg 264 #1/2 a,c• Check answers- Pg 592
• Now try the summary problems Pg 265 #1-7
• Solutions on how to do them are on the following page
Reaction Rates
• How fast a reaction occurs• Can be fast or slow
Temperature
• Increase temp = increase rxn rate• Decrease temp = decrease rxn
rate• Warmer = molecules move faster
= more collisions
Concentration
• Increased conc = increased rxn rate
• Decreased conc = decreased rxn rate
• More molecules = faster rxn
Surface Area
• Increase SA = increase rxn rate• Decrease SA = decrease rxn rate• What burns faster: kindling or a
large log?
Catalyst
• Speeds up a rxn but is not used up• Lower energy needed for rxn to
start• Eg: enzymes in your body• Eg: catalytic converter in cars