Reaction Type Notes. Most chemical reactions can be categorized into one of five types. You can usually identify the reaction type by looking at the

Reaction Type Reaction Type NotesNotes

Reaction Type NotesReaction Type Notes Most chemical reactions can Most chemical reactions can

be categorized into one of be categorized into one of fivefive types.types.

You can usually identify the You can usually identify the reaction type by looking at the reaction type by looking at the reactantsreactants. Once the type of . Once the type of reaction is identified, we can reaction is identified, we can predict the predict the productsproducts..

Reaction Type NotesReaction Type Notes

Chemists classify reactions in order to organize the many types:

• 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 orAB + CD ABCD

Types of Chemical Reactions• When two elements react, the

reaction is always a synthesis reaction.


Example:Example: 2 H 2 H22 + O + O22 2 2

HH22OO


Synthesis:Synthesis: To predict the products: for binary To predict the products: for binary

compounds, put elements together compounds, put elements together and and balancebalance the the total chargestotal charges. . Otherwise, just combine.Otherwise, just combine.

These reactions generally happen These reactions generally happen spontaneouslyspontaneously, and are generally , and are generally exothermicexothermic (release energy). (release energy).

Types of Chemical Reactions• In a combustion reaction, oxygen

combines with another substance and releases energy in the form of heat and light.

• Heated hydrogen reacts with oxygen to produce heat and water in a combustion reaction. This is also a synthesis reaction.


HydrocarbonHydrocarbon combustion—a combustion—a specific case of combustion in which specific case of combustion in which a hydrocarbon (a substance only a hydrocarbon (a substance only containing containing carboncarbon and and hydrogenhydrogen) ) reacts with oxygen to form carbon reacts with oxygen to form carbon dioxide and waterdioxide and water

General form: General form: CCxxHHyy + O + O22 CO CO22 + +

HH22OO


Example:Example:

2C2C22HH66 + 7O + 7O22 4CO 4CO22 + 6H + 6H22OO


Hydrocarbon Combustion:Hydrocarbon Combustion: To predict products:To predict products: At least carbon dioxide and At least carbon dioxide and

water. Always water. Always exothermicexothermic, but , but often requires a large often requires a large activation activation energyenergy, keeping it from , keeping it from happening spontaneously.happening spontaneously.

Decomposition Reactions

• A decomposition reaction is one in w hich a single compound breaks down into two or more elements or new compounds.

• Decomposition reactions often require an energy source, such as heat, light, or electricity, to occur and be maintained.

• General form: AB A + B


Example:Example: 2H 2H22OO22 2 H 2 H22O + OO + O22

(Needs a (Needs a catalystcatalyst—Potassium Iodide)—Potassium Iodide)


Decomposition:Decomposition:

To predict the products:To predict the products: Binary compoundsBinary compounds separate into separate into

their two elements.their two elements. You will be given a handout to You will be given a handout to

predict others.predict others. Generally not Generally not spontaneousspontaneous, and , and

generally generally endothermic.endothermic.

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

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.


• Anions can replace anions in compounds. Halogens frequently replace other halogens in replacement reactions.

• Halogens also have different reactivities, like metallic elements. There is a separate activity series for anions.


Example:Example: 2 Na + 2 H(OH) 2 Na + 2 H(OH) 2 2 Na(OH)Na(OH)+ H+ H22


Single displacement:Single displacement: To predict the products: The element To predict the products: The element

switches places with the element of switches places with the element of similar similar chargecharge within the compound. within the compound.

If the element is If the element is more reactivemore reactive, then the , then the one it attempts to replace, then the one it attempts to replace, then the reaction will be reaction will be spontaneousspontaneous and and exothermicexothermic. Otherwise, it will not be . Otherwise, it will not be spontaneous and will be spontaneous and will be endothermicendothermic (require the input of energy).(require the input of energy).

Activity Series:Activity Series:Most Active Most Active CationsCations

Least ActiveLeast Active LithiumLithium RubidiumRubidium PotassiumPotassium BariumBarium CalciumCalcium SodiumSodium MagnesiumMagnesium AluminumAluminum ManganeseManganese

ZincZinc ChromiumChromium IronIron NickelNickel TinTin LeadLead HydrogenHydrogen CopperCopper MercuryMercury SilverSilver PlatinumPlatinum GoldGold

*Red not included in book values*Red not included in book values


Activity Series:Activity Series:Most Active Most Active AnionsAnions

Least ActiveLeast Active FluorineFluorine OxygenOxygen ChlorineChlorine NitrogenNitrogen BromineBromine IodineIodine

SulfurSulfur SeleniumSelenium AstatineAstatine PhosphorusPhosphorus TelluriumTellurium ArsenicArsenic PoloniumPolonium

*Red not included in book *Red not included in book valuesvalues


Reaction Type NotesReaction Type Notes• Double replacement reactions

occur when ions are exchanged between two compounds.

• This figure shows the form of a double replacement equation.


Double displacement:Double displacement:To predict the products:To predict the products: Like chargedLike charged particles switch places particles switch places Both compounds are initially Both compounds are initially stablestable and and

so reactions will usually not be so reactions will usually not be spontaneous as solids. If compounds spontaneous as solids. If compounds can be dissolved and dissociated can be dissolved and dissociated (broken apart) then the reaction will (broken apart) then the reaction will usually occur usually occur spontaneouslyspontaneously to some to some degree, but not be degree, but not be highly exothermic.highly exothermic.

Example:Example: 2 NaI(aq) + Pb(NO 2 NaI(aq) + Pb(NO33))22(aq) (aq)

PbIPbI22(s) + 2NaNO(s) + 2NaNO33(aq) (aq)

• 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.


• This table shows the steps to write double replacement reactions.



MostMost reactions which do reactions which do not appear to fit any of not appear to fit any of these five patterns are these five patterns are usually a usually a combination combination of of two or more of them two or more of them happening simultaneously.happening simultaneously.


Practice Problem ANSWERS (page 291):Practice Problem ANSWERS (page 291):

14.14. 2 Al(s) + 3 S(s) 2 Al(s) + 3 S(s) Al Al22SS33; synthesis; synthesis

15.15. HH22O(l) + NO(l) + N22OO55(g) (g) 2HNO 2HNO33(aq); (aq); synthesissynthesis

16.16. 4 NO4 NO22(g) + O(g) + O22(g) (g) 2N 2N22OO55(g); (g); synthesis and combustionsynthesis and combustion

17.17. HH22SOSO44(aq) + 2NAOH(aq) (aq) + 2NAOH(aq) Na Na22SOSO44 (aq) (aq) + 2H+ 2H22O(l); synthesisO(l); synthesis


Practice Problem ANSWERS Practice Problem ANSWERS (page (page 292):292):

18.18. 2Al2Al22OO33(s) (s) 4 Al(s) 4 Al(s) + 3O+ 3O22(g)(g)

19.19. Ni(OH)Ni(OH)22(s) (s) NiO(s) + 2H NiO(s) + 2H22O(l)O(l)

20.20. 2 NaHCO2 NaHCO33(s) (s) Na Na22COCO33(aq) + (aq) + COCO22(g) + H(g) + H22O(l)O(l)


Textbook Practice (page 295):Textbook Practice (page 295):

Problems #21-#24.Problems #21-#24. Answer in your lab Answer in your lab

composition journal.composition journal.


Textbook Practice ANSWERS:Textbook Practice ANSWERS:

21.21. 2K(s) + ZnCl2K(s) + ZnCl22(aq) (aq) Zn(s) Zn(s) + 2KCl(aq)+ 2KCl(aq)

22.22. No Reaction—Cl is below F in the No Reaction—Cl is below F in the activity seriesactivity series

23.23. No Reaction—Fe is below Na in the No Reaction—Fe is below Na in the activity series activity series

24.24. 2Al(s) + 3Pb(NO2Al(s) + 3Pb(NO33))22(s) (s) 3Pb(s) + 3Pb(s) +

2Al(NO2Al(NO33))33(aq)(aq)


Textbook Practice (page 297):Textbook Practice (page 297):

Problems #25-#27.Problems #25-#27. Answer in your lab Answer in your lab

composition journal.composition journal.


Textbook Practice ANSWERS:Textbook Practice ANSWERS:

25.25. LiI(aq) + AgNOLiI(aq) + AgNO33(aq) (aq) AgI(s) AgI(s) + + LiNOLiNO33(aq)(aq)

26.26. BaClBaCl22(aq) + K(aq) + K22COCO33(aq) (aq) BaCO BaCO33(s) + (s) + 2KCl(aq)2KCl(aq)

27.27. NaNa22CC22OO44(aq) + Pb(NO(aq) + Pb(NO33))22(aq) (aq) PbCPbC22OO44(s) + 2NaNO(s) + 2NaNO33(aq)(aq)


• This table summarizes different ways to predict the products of a chemical reaction.


The following equation is what type of reaction?The following equation is what type of reaction?

KCN(aq) + HBr(aq) → KBr(aq) + HCN(g) KCN(aq) + HBr(aq) → KBr(aq) + HCN(g)

A.A. deconstructive deconstructive

B.B. synthesis synthesis

C.C. single replacement single replacement

D.D. double replacement double replacement


Which of the following is NOT one of Which of the following is NOT one of the four types of reactions? the four types of reactions?

A.A. deconstructive deconstructive

B.B. synthesis synthesis

C.C. single replacement single replacement

D.D. double replacement double replacement

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Reaction Type Notes. Most chemical reactions can be categorized into one of five types. You can usually identify the reaction type by looking at the