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I. 5 Main Types of Reactions. 1. Synthesis. 2 substances combine to form a compound. Example: 4Fe + 3O 2 2Fe 2 O 3 2 reactants 1 product. 2. Decomposition. A COMPOUND BREAKS DOWN INTO 2 OR MORE SIMPLER SUBSTANCES. NH 4 NO 3 N 2 O + H 2 O 1 reactant .
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1. Synthesis 2 substances combine to form a compound. Example: 4Fe + 3O2 2Fe2O3 2 reactants 1 product
2. Decomposition A COMPOUND BREAKS DOWN INTO 2 OR MORE SIMPLER SUBSTANCES NH4NO3 N2O + H2O 1 reactant More than 1 product
3. Single Displacement • Rxn where 1 element takes the place of another • Example Fe + CuSO4 FeSO4 + Cu Element, compound Element, compound
4. Double Displacement • Rxn where the + portion of 2 ionic compounds are interchanged • Example: Pb(NO3) 2 + 2KI KNO3 + PbI2 compound, compound compound, compound
5. Combustion • Rxn where a substance rapidly combines with Oxygen to form 1 or more oxides • Example: 2C2H2 + 5O2 4CO2 + 2H2O + Energy O is a reactant
A. Reversible Rxns • Can change direction • Equilibrium – rxn that automatically reverses & there is no overall change in the amount of products or reactants.
Reversible Rxns Cont. 3. Example: CaCO3(s) CaO(s) + CO2 (g) limestone lime 4. The double arrow shows that the rxn can go either way.
5. Equilibrium can “disturbed” in order to increase the yield of desired product in a rxn. Example: CaCO3 CaO + CO2 a. If you take out the CO2 the rxn will shift right to produce more lime
b. Adding E can push a rxn to the left or right. 1. Example: 3C + 2Al2O3(s) + E 4Al + 3CO2 (g) Endo to the right Exo to the left When you add more E, more product is formed. 2. Example: N2 + H2 NH3 + E Exo to the right Endo to the left Adding more E pushes the rxn left
B. Reaction Rate • Activation Energy –the amt of E required to make a rxn occur
Ways to increase Reaction rates • Raising temps • Increasing Concentration- amt of a substance present in a given volume Ex: fanning flames 3. If gases are involved, the rate of rxn can be increased by increasing pressure.
Rxn Rate Cont. • Increasing Surface Area- crushing or breaking substances into smaller pieces increase rxn rates. • Add a Catalyst – substance that speeds up the rxn rate without being permanently changed or used up itself In the body they are called enzymes
Slowing Reactions • Do the opposite of any way to speed rxns up. • Inhibitor – slows a rxn without participating