Chemical Reaction TypesChemical Reaction Types

Reaction Types I Need to Reaction Types I Need to KnowKnow

Combustion Reactions Combustion Reactions

Combustion means the reaction of Combustion means the reaction of oxygen with a compound usually oxygen with a compound usually containing carbon and hydrogen. A containing carbon and hydrogen. A common synonym for combustion iscommon synonym for combustion is

Combustion ReactionsCombustion Reactions

Written using generic symbols, it is Written using generic symbols, it is usually shown as: usually shown as:

CCxxHHyy + O + O22 ---> CO ---> CO22 + H + H22O O

These are some examples: CH4 + O2 --->

C2H6 + O2 ---> C6H12O6 + O2 ---> C2H5OH + O2 --->

CombustionCombustion

Notice that some compounds contain Notice that some compounds contain carbon, hydrogen AND oxygen.carbon, hydrogen AND oxygen.

However, the products are all the However, the products are all the same, in every reaction. Isn't that same, in every reaction. Isn't that great? great?

Combustion ReactionsCombustion Reactions

How to figure out the product side: How to figure out the product side: (#1) Identify the reaction as combustion: (#1) Identify the reaction as combustion:

A carbon-hydrogen compound reacting with A carbon-hydrogen compound reacting with oxygen oxygen

(#2) Know that the combustion products are (#2) Know that the combustion products are always COalways CO22 and H and H22O So the final answer looks O So the final answer looks like this: like this:

CC77HH66O + OO + O22 ---> CO ---> CO22 + H + H22O O

THEN BALANCE!!!THEN BALANCE!!!

CHCH33COCHCOCH33 + O + O22 ---> --->

HH22CC22OO44 + O + O22 ---> --->

Synthesis ReactionsSynthesis Reactions

Synthesis are almost always the reverse of a Synthesis are almost always the reverse of a decomposition reaction. decomposition reaction.

That means that two pieces join together to produce That means that two pieces join together to produce one, more complex compound. one, more complex compound.

These pieces can be elements or simpler These pieces can be elements or simpler compounds. compounds.

Complex simply means that the product compound Complex simply means that the product compound has more atoms than the reactant molecules. has more atoms than the reactant molecules.

Written using generic symbols, it is usually shown Written using generic symbols, it is usually shown as: as:

A + B ---> AB A + B ---> AB

Synthesis ReactionsSynthesis ReactionsThese are some examples: These are some examples:

Mg + OMg + O22 ---> MgO ---> MgOHH22 + O + O22 ---> H ---> H22OOK + ClK + Cl22 ---> KCl ---> KCl

Fe + OFe + O22 ---> Fe ---> Fe22OO33

Synthesis can also be two compounds making a Synthesis can also be two compounds making a more complex compound (or a compound and an more complex compound (or a compound and an element joining together) as in these examples: element joining together) as in these examples:

CaO + COCaO + CO22 ---> CaCO ---> CaCO33

NaNa22O + COO + CO22 ---> Na ---> Na22COCO33

KCl + OKCl + O22 ---> KClO ---> KClO33

Ba(ClOBa(ClO33))22 ---> BaCl ---> BaCl22 + O + O22

Decomposition ReactionsDecomposition Reactions

During decomposition, one During decomposition, one compound splits apart into two (or compound splits apart into two (or more pieces). These pieces can be more pieces). These pieces can be elements or simpler compounds elements or simpler compounds

Written using generic symbols, it is Written using generic symbols, it is usually shown as: usually shown as:

AB ---> A + B AB ---> A + B

Decomposition ReactionsDecomposition ReactionsAB ---> A + B AB ---> A + B

However, that really only works for However, that really only works for splitting apart into the elements, like splitting apart into the elements, like these examples. these examples.

HgO ---> Hg + OHgO ---> Hg + O22

H2O ---> HH2O ---> H22 + O + O22

MgClMgCl22 ---> Mg + Cl ---> Mg + Cl22

FeS ---> Fe + SFeS ---> Fe + S

Decomposition ReactionsDecomposition Reactions

Decomposition can also split one compound Decomposition can also split one compound into two simpler compounds (or compound into two simpler compounds (or compound and an element) as in these examples: and an element) as in these examples:

CaCOCaCO33 ---> CaO + CO ---> CaO + CO22

NaNa22COCO33 ---> Na ---> Na22O + COO + CO22

KClOKClO33 ---> KCl + O ---> KCl + O22

Ba(ClOBa(ClO33))22 ---> BaCl ---> BaCl22 + O + O22 Notice how, in every case so far, there is Notice how, in every case so far, there is

only one substance on the left-hand only one substance on the left-hand (reactant) side. This is always the case in a (reactant) side. This is always the case in a decomposition reaction. Don't forget that!! decomposition reaction. Don't forget that!!

ACTIVITY SERIESACTIVITY SERIES

Appendix A of your Book p. 832Appendix A of your Book p. 832 Most active one is at the topMost active one is at the top An element can displace those An element can displace those

listed below it, but not above itlisted below it, but not above it

How to Use the Activity How to Use the Activity SeriesSeries

p. 281 in your bookp. 281 in your book• Identify the reactants (metal or Identify the reactants (metal or

halogen) and if the element would halogen) and if the element would be displacedbe displaced

• Check the activity seriesCheck the activity series• Write the productsWrite the products• Balance the equationBalance the equation

Single Replacement Single Replacement ReactionsReactions

During single replacement, one During single replacement, one element replaces another element in element replaces another element in a compound. There are two different a compound. There are two different possibilities: possibilities: 1. One cation replaces another. 1. One cation replaces another.

AX + Y ---> YX + A AX + Y ---> YX + A

2. One anion replaces another. 2. One anion replaces another. A + XY ---> XA + Y A + XY ---> XA + Y

Single Replacement Single Replacement ReactionsReactions

1. One cation replaces another. 1. One cation replaces another. Written using generic symbols, it is: Written using generic symbols, it is:

AX + Y ---> YX + A AX + Y ---> YX + A Element Y has replaced A (in the Element Y has replaced A (in the

compound AX) to form a new compound AX) to form a new compound YX and the free element A. compound YX and the free element A.

Cu + AgNOCu + AgNO33 ---> Ag + Cu(NO ---> Ag + Cu(NO33))22

Fe + Cu(NOFe + Cu(NO33))22 ---> Fe(NO ---> Fe(NO33))22 + Cu + CuCa + HCa + H22O ---> Ca(OH)O ---> Ca(OH)22 + H + H22

Zn + HCl ---> ZnClZn + HCl ---> ZnCl22 + H + H22

Single ReplacementSingle Replacement

2. One anion replaces another. Written 2. One anion replaces another. Written using generic symbols, it is: using generic symbols, it is:

A + XY ---> XA + Y A + XY ---> XA + Y Element A has replaced Y (in the Element A has replaced Y (in the

compound XY) to form a new compound compound XY) to form a new compound XA and the free element Y. XA and the free element Y.

Remember that A and Y are both anions Remember that A and Y are both anions (negatively-charged ions) in this example. (negatively-charged ions) in this example.

ClCl22 + NaBr ---> NaCl + Br + NaBr ---> NaCl + Br22

BrBr22 + KI ---> KBr + I + KI ---> KBr + I22

Single ReplacementSingle Replacement

In single replacement, one reactant is always an In single replacement, one reactant is always an element. element.

Typically, you will be given the left-hand (reactant Typically, you will be given the left-hand (reactant

side) and asked to provide the products to the side) and asked to provide the products to the reaction. reaction.

You need to be able to recognize single You need to be able to recognize single replacement reactions AND be able to break a replacement reactions AND be able to break a formula apart into proper cations and anions as formula apart into proper cations and anions as well as write correct formulas well as write correct formulas

Practice ProblemsPractice Problems

1) ZnS + Fe --->1) ZnS + Fe --->

2) K + H2) K + H22O --->O --->

3) Fe + HCl --->3) Fe + HCl --->

4) NaI + Br4) NaI + Br22 ---> --->

Double Replacement Double Replacement ReactionsReactions

During double replacement, the During double replacement, the cations and anions of two different cations and anions of two different compounds switch places. compounds switch places.

Written using generic symbols, it is: Written using generic symbols, it is:

AB + XY ---> AY + XB AB + XY ---> AY + XB A and X are the cations in this A and X are the cations in this

example, with B and Y being the example, with B and Y being the anionsanions

Double Replacement Double Replacement ExamplesExamples

KOH + HKOH + H22SOSO44 ---> --->

FeS + HCl ---> FeS + HCl --->

NaCl + HNaCl + H22SOSO44 ---> ---> AgNOAgNO33 + NaCl ---> + NaCl --->

p. 284 Identify Reactions and p. 284 Identify Reactions and Predict ProductsPredict Products

Solubility Chart with Solubility RulesSolubility Chart with Solubility Rules

REMEMBER….REMEMBER….

If you’re not part of the solution, you If you’re not part of the solution, you are part of the precipitate. ----Eric are part of the precipitate. ----Eric DeschDesch