section 8.2 types of chemical reactions combination reactions decomposition reactions...

Section 8.2 Types of Chemical Reactions

Combination ReactionsDecomposition Reactions

Single-Replacement ReactionsDouble-Replacement Reactions

Combustion Reactions(complete and incomplete)

Please turn to page 3 in your Note Pack, and have your Periodic Table available as a resource.

8.2 Types of ReactionsCOMBINATION REACTIONS

A. What is a combination reaction? (sometimes called a synthesis reaction or composition reaction)

Two or more substances combine to form a single substance.


B. Write a general equation for a combination reaction:

A + B AB

There are some ways we can remember these reactions and how to predict their products.


4 Good things to know about combination reactions…



1 When a metal combines with a nonmetal, use their _____________ ___________ to figure out the product.

(forms an ionic compound called a ___________)



1 When a metal combines with a nonmetal, use their oxidation numbers to figure out the product.

(forms an ionic compound called a ___________)




(forms an ionic compound called a formula unit)

Ox. #’s are the possible charges an element CAN potentially get (O = -2; Al = +3; Cu = +2 or +3)


4 Good things to know about combination reactions… (Fill in examples)


(forms an ionic compound called a formula unit)

Example: Potassium metal reacts with Chlorine gas



1 When a metal combines with a nonmetal, use their oxidation numbers to figure out the product.(forms an ionic compound called a formula unit)


K K (s)(s) + Cl + Cl22 (g)(g)





K K (s)(s) + Cl + Cl22 (g)(g) K K++ Cl Cl--





K K (s)(s) + Cl + Cl22 (g)(g) KCl KCl …but it’s not balanced yet.





2K 2K (s)(s) + Cl + Cl22 (g)(g) 2KCl 2KCl (s)(s)




Next Example: Nickel (II) reacts with Oxygen gas

Ni + ONi + O22





Ni + ONi + O22 Ni Ni+2+2 + O + O-2-2





2Ni + O2Ni + O22 Ni Ni+2+2 + O + O-2-2 2NiO2NiO


• When two nonmetals combine, you cannot figure out the product based on oxidation numbers

There could be a number of possible combinations for these molecules.

(forms a molecule and therefore we must rely on observation to predict product)


• When two nonmetals combine, you cannot figure out the product based on oxidation numbers



Example: Chlorine gas reacts with bromine gas to produce trichlorine pentabromide solid.


2 When two nonmetals combine, you cannot figure out the product based on oxidation numbers




ClCl22 + Br + Br22






ClCl22 + Br + Br22 Cl Cl33BrBr5 (not balanced, yet)5 (not balanced, yet)






3 Cl3 Cl22 + 5 Br + 5 Br22 2 Cl 2 Cl33BrBr5 (now its balanced)5 (now its balanced)


• When a nonmetal oxide reacts with water, it will produce an Acid.



Examples might include:

N2O5 P2O5 SO3



Start by writing the H first (that’s what makes it

an acid), and end with the O.



(start with the H and end with the O)

Example: Sulfur dioxide gas reacts with water


• When a nonmetal oxide reacts with water, it will produce an Acid. (start with the H and end with the O)


SOSO22 (g)(g) + H + H22O O ((ll))





SOSO22 (g)(g) + H + H22O O ((ll)) H H22SOSO33 (aq)(aq) , , sulfurous acidsulfurous acid




Next Example: Gaseous dinitrogen pentoxide gas reacts with water


• When a nonmetal oxide reacts with water, it will produce an Acid.(start with the H and end with the O)


NN22OO55 (g)(g) + H + H22O O ((ll)) ??? ???


• When a nonmetal oxide reacts with water, it will produce an Acid.(start with the H and end with the O)


NN22OO55 (g)(g) + H + H22O O ((ll)) HH22NN22OO66 = 2HNO = 2HNO33Empirical formula


• When a metal oxide reacts with water, it will produce a Base.

Remember [H2O = H+ OH-]

Examples of metal oxides include:

Copper (II) oxide CuO

Aluminum oxide Al2O3

Sodium oxide Na2O



(start with the metal and end with hydroxide, OH-)




Example: Sodium oxide reacts with water.





NaNa22O O (s)(s) + H + H22O O ((ll)) ??????





NaNa22O O (s)(s) + H + H22O O ((ll)) 2NaOH 2NaOH (aq)(aq)


Now its your turn…With a neighbor, work through the following.

Practice Examples: Write the balanced equations for the following combinations.


Practice Examples: Write the balanced equations for the following combinations…

1 Beryllium metal reacts with oxygen gas



1 Beryllium metal reacts with oxygen gas

Be + O2 Be+2 + O-2 2BeOBalanced, it looks like this…

2Be + O2 2BeO



2 Gaseous dinitrogen pentoxide reacts with water



2 Gaseous dinitrogen pentoxide reacts with water

N2O5 + H2O H2N2O6 = 2HNO3Empirical formula



3 Nitrogen gas reacts with lumps of sulfur to produce trinitrogen monosulfide.



3 Nitrogen gas reacts with lumps of sulfur to produce trinitrogen monosulfide.

3N2 (g) + 2S (s) 2N3S



4 Chunks of Calcium oxide is dropped into water



4 Chunks of Calcium oxide is dropped into water

CaO + H2O Ca(OH)2



5 Aluminum metal rusts



5 Aluminum metal rusts

Al + O2 Al+3 + O-2 Al2O3Balanced, it looks like this,

4Al + 3O2 2Al2O3


Please use your notes, and really focus on the Helpful Hints as you predict the products of the Combination Reactions.

section 8.2 types of chemical reactions combination reactions decomposition reactions...

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