Classifying Chemical Reactions

Determining reaction types and predicting products of chemical

equations.

Reaction Types

• There is an unlimited number of reactions that may occur in the real world.

• To make learning them easier, we classify them according to what is taking place.

• Makes predicting products MUCH easier.

Combustion Reactions

• Often used to generate energy.

• Combustion Reaction – the oxidation of an organic compound, in which heat is released.

• One reactant is a hydrocarbon and the other must be ______________.

• Products are always carbon dioxide and water.

Combustion Reactions

Examples:___C3H8 + ___O2 ___H2O + ___CO2

___C2H5OH + ___ ___ + ___

Write down the combustion of CH4

Synthesis Reaction

• The word synthesis means “to put together”

• Synthesis Reaction – a reaction in which two or more substances combine to form a new compound.

• The reactants in many of these reactions are two elements or two small compounds.

Synthesis Reactions

C + O2 CO2 2C + O2 2CO

CaO(s) + H2O(l) Ca(OH)2(s)

Predict the products of the following synthesis rxns:K + Cl2

Mg + O2

Decomposition Reaction

• Decomposition reactions are the opposite of synthesis reactions – they have only one reactant.

• In a decomposition reaction, a single compound breaks down, often with the input of energy, into two or more elements or simpler compounds.

Decomposition Reactions

Water breaks down into its simpler components when introduced to electricity:

2H2O(l) ---------> 2H2(g) + O2(g)

Compounds made up of three or more elements usually do not decompose into those elements.

CaCO3(s) -------> CaO(s) + CO2(g)

Electricity

Heat

Practice So Far:

• Predict the product(s) and write a balanced equation for each of the following reactions:– The reaction of butane, C4H10, with oxygen.

– The reaction of water and calcium oxide

– The reaction of lithium with oxygen

– The decomposition of carbonic acid.

Displacement Reactions

• Single displacement (replacement) reaction-– A single element reacts with a compound and

displaces another element of the same charge from the compound.

• Examples:2Al(s) + 3CuCl2(aq) 2AlCl3(aq) + 3Cu(s)

• Predict the following products:CuSO4(aq) + Zn(s)

Activity Series, Page 281

• Used to make predictions about displacement reactions.

• In the activity series, elements are arranged in order of activity with the most active on top.

• In general, an element can displace those listed below it but not those above it.

• You could also predict that no reaction will happen, such as when silver is put into a copper (II) nitrate soln.

Displacement Reactions

• Double displacement (replacement) reaction-– Two compounds react with one another and swap

cations / anions.

• Examples:HCl(aq) + NaOH(aq) HOH(l) + NaCl(s)

• Predict the following products:Cu(NO3)2(aq) + Al2(SO4)3(s)

Practice Classifying Reactions

• Balance each of the equations below, and indicate the type of reaction for each equation

___Cl2(g) + ___NaBr(aq) ___NaCl(aq) + ___Br2(l)

___CaO(s) + ___H2O ___Ca(OH)2(aq)

___Ca(ClO3)2(s) ___CaCl2(s) + ___O2(g)

Practice Classifying Reactions

• Balance each of the equations below, and indicate the type of reaction for each equation

___C8H18(l) + ___O2(g) ___CO2(g) + ___H2O(l)

__Zn(s) + __CuBr2(aq) __ZnBr2(aq) + __Cu(s)

__AgNO3(aq) + __K2SO4(aq) __Ag2SO4 + __KNO3(aq)

Practice With Activity Series

• Predict whether a reaction would occur when the materials indicated are brought together. For each reaction that would occur, complete and balance the equation.

___Ag(s) + ___H2O(l)

___Mg(s) + ___Cu(NO3)2(aq)

___Al(s) + ___O2(g)

___H2SO4(aq) + ___KOH(aq)

Predicting Products

• Predict the products, write a balanced equation, and identify the type of reaction for each of the following reactions.

HgO

C3H7OH + O2

Zn + CuSO4

Predicting Products

• Predict the products, write a balanced equation, and identify the type of reaction for each of the following reactions.

BaCl2 + Na2SO4

Zn + F2

C5H10 + O2

• Finishing up the Chapter tomorrow (Net Ionic Equations).

• Test Coming up!!

• Start Practicing NOW!– Describing, Balancing,

and Classifying Reactions