Download presentation
Presentation is loading. Please wait.
1
Types of Reactions Notes
Section 9.2
2
Reaction Type Notes Most chemical reactions can be categorized
into one of five types. 1. Synthesis/Composition Reactions 2. Decomposition Reactions 3. Single Replacement Reactions 4. Double Replacement Reactions (Precipitates) 5. Combustion Reactions
3
You can usually identify the reaction type by looking at the reactants.
Once the type of reaction is identified, we can predict the products.
4
1. Synthesis/Composition Reactions
A synthesis reaction is a reaction in which two or more substances react
to produce a single product. General form: A + B AB or A + BC ABC AB + CD ABCD
5
When only two elements react, the
reaction is always a synthesis
reaction.
6
Example: 2 H2 + O2 2 H2O Draw the reaction.
7
Generally exothermic (release energy).
1. Synthesis/Composition Reactions These reactions generally happen spontaneously (automatically). Generally exothermic (release energy).
8
2. Decomposition Reactions
A decomposition reaction is one in which a single compound breaks down into two or more elements or new compounds. General form: AB A + B
9
Example: 2H2O2 2 H2O + O2 (it needs a catalyst—Potassium Iodide) More Typical Example:
10
To predict the products:
2. Decomposition Reactions To predict the products: Binary compounds separate into their two elements Check back of yellow periodic table handout for other decomposition predictions.
11
Endothermic reactions (need energy to start, do not release energy).
2. Decomposition Reactions These reactions are not spontaneous. Need a form of energy or catalyst to make the reaction occur. Endothermic reactions (need energy to start, do not release energy).
12
Synthesis or Decomposition?
1. KClO3 KCl +
O2 1. Zn + S ZnS 2. 3. Al2S3 Al S 3. Fe + O2 Fe2O3 4. Na Cl2 NaCl 5. H2O H O2 6. Synthesis or Decomposition? 1. KClO3 KCl + O2 2. Zn S ZnS 3. Al2S3 Al S 4. Fe O2 Fe2O3 5. Na Cl2 NaCl 6. H2O H O2
13
Reaction Type Notes Practice pg . 292 18. 2Al2O3(s) 4 Al(s) + 3O2(g)
19. Ni(OH)2(s) NiO(s) + H2O(l) NaHCO3(s) Na2CO3(aq) + CO2(g) + H2O(l)
14
Practice: Pg. 313 Numbers 85 and 87
85. a. 2 B (s) + 3 F2 (g) --> 2BF3 (g) b. Ge (s) + 2 S (s) --> GeS2 (s) c. 3 Zr (s) + 2 N2 (g) --> Zr3N4 (s) d. P4O10 (s) + 6 H2O (l) --> 4 H3PO4 (aq) 87. a. MgBr2 (S) --> Mg (s) + Br2 (l) b. 2 CoO (s) --> 2 Co (s) + O2 (g) c. Ti(OH)4 (s) --> TiO2 (s) + 2 H2O (l) d. BaCO3 (s) --> BaO (s) + CO2 (g)
15
General form: A + BX → AX + B
3. Replacement Reactions A reaction in which the atoms of one element replace the atoms of another element in a compound is called a single replacement reaction. General form: A + BX → AX + B
16
3. Replacement Reactions (cont.)
A metal will not always
replace a metal in a
compound dissolved in
water because of differing
reactivities. An activity series can
be used to predict if
reactions will occur.
17
Halogens frequently replace other halogens in replacement reactions.
3. Replacement Reactions (cont.) Halogens frequently replace other halogens in replacement reactions. Thus, halogens (and other anions) are a part of the activity series along with metal (cations).
18
Example: 2 Na + 2 H(OH) 2 Na(OH)+ H2
19
To predict the products: The element switches places with the element of similar charge within the compound. If the element is more reactive then the one it attempts to replace, then the reaction will be spontaneous and exothermic. Otherwise, it will not be spontaneous and will be endothermic (require the input of energy).
20
Activity Series: Most Active Cations Least
Lithium Rubidium Potassium Barium Calcium Sodium Hydrogen (in water) Magnesium Aluminum Manganese Zinc Chromium Iron Nickel Tin Lead Hydrogen (in acids) Copper Mercury Silver Platinum Gold *Red not included in book values
21
Activity Series: Most Active Anions Least
Fluorine Oxygen Chlorine Nitrogen Bromine Iodine Sulfur Selenium Astatine Phosphorus Tellurium Arsenic Polonium *Red not included in book values
22
Reaction Type Notes Practice p. 295
21. 2K(s) + ZnCl2(aq) Zn(s) + 2KCl(aq) 22. No Reaction—Cl is below F in the activity
series 23. No Reaction—Fe is below Na in the activity
series 24. 2Al(s) + 3Pb(NO3)2(s) 3Pb(s) + 2Al(NO3)3(aq)
23
4. Double Replacement Reactions
Double replacement reactions
occur when ions exchange
between two compounds. General Form:
24
To predict the products: Like charged particles switch places
4. Double Replacement Reactions To predict the products: Like charged particles switch places Both compounds are initially stable and so reactions will usually not be spontaneous as solids. If compounds can be dissolved and dissociated
(broken apart) then reaction will usually occur spontaneously to some degree, but not be highly exothermic.
25
4. Double Replacement Reactions (cont.)
A solid product produced during a chemical reaction in a solution is called a precipitate. All double replacement reactions produce either water, a precipitate, or a gas.
26
Example: 2 NaI(aq) + Pb(NO3)2(aq) PbI2(s) + 2NaNO3(aq)
27
Reaction Type Notes Practice p. 297
25. LiI(aq) + AgNO3(aq) AgI(s) + LiNO3(aq) 26. BaCl2(aq) + K2CO3(aq) BaCO3(s) + 2KCl(aq) 27. Na2C2O4(aq) + Pb(NO3)2(aq) PbC2O4(s) + 2NaNO3(aq)
28
5. Combustion Reactions In a combustion reaction,
oxygen combines with a substance
and releases energy in the form of
heat and light.
29
5. Combustion Reactions Hydrocarbon Combustion—Involves a specific case of combustion in which a
hydrocarbon (a substance containing carbon and hydrogen) reacts with oxygen to form carbon dioxide and water General form: CxHy + O2 CO2 + H2O
30
5. Combustion Reactions Example: 2C2H6 + 7O2 4CO2 + 6H2O
31
To predict products: Will always include carbon dioxide and water.
5. Combustion Reactions To predict products: Will always include carbon dioxide and water. Always exothermic, but often requires a large activation energy (not truly spontaneous).
32
Reaction Type Notes Practice p. 291
Al(s) + 3 S(s) Al2S3; synthesis 15. H2O(l) + N2O5(g) 2HNO3(aq); synthesis 16. 4 NO2(g) + O2(g) 2N2O5(g); synthesis and combustion
33
Reaction Type Notes Most reactions which do not appear to fit any of these five patterns are usually a combination of two or more of them happening simultaneously
34
PRACTICE - Identify the type of reaction.
1. ___Fe + ___ HCl ___ FeCl2 + ___H2 2. ___Al + __ H2SO4 __ Al2(SO4)3 + __ H2 3. ___Pb(NO3)2 + __ H2S __ PbS + __ HNO3 4. ___Na2CO3 + __ HCl __ NaCl + __H2CO3 5. ___C2H2 + ___O2 ___ CO2 + ___H2O 6. ___C6H14 + ____ O2 ___ CO2 + ___H2O
35
Replacement Reactions (cont.)
This table summarizes different
ways to predict the products of a
chemical reaction.
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.