Section 8.2 Types of Chemical Reactions - Reeths

Section 8.2

Types of Chemical Reactions

Combination Reactions

Decomposition Reactions

Single-Replacement Reactions

Double-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 Reactions

COMBINATION 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)



Example: Potassium metal reacts with Chlorine gas




(Fill in examples)




K

(s)

+ Cl

2 (g)






(Fill in examples)




K

(s)

+ Cl

2 (g)

 K + Cl -




(Fill in examples)




K

(s)

+ Cl

2 (g)

 KCl

…but it’s not balanced yet.




(Fill in examples)




2K

(s)

+ Cl

2 (g)

 2KCl

(s)





Next Example : Nickel (II) reacts with Oxygen gas

Ni + O

2






Ni + O

2

 Ni +2 + O -2






2Ni + O

2

 Ni +2 + O -2  2NiO



• 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




Cl

2

+ Br

2









Cl

2

+ Br

2

 Cl

3

Br

5 (not balanced, yet)







3 Cl

2

+ 5 Br

2

 2 Cl

3

Br

5 (now its balanced)



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




Examples might include:

N

2

O

5

P

2

O

5

SO

3




 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






SO

2 (g)

+ H

2

O

(l)






SO

2 (g)

+ H

2

O

(l)

 H

2

SO

3 (aq)

, sulfurous acid





Next Example: Gaseous dinitrogen pentoxide gas reacts with water






N

2

O

5 (g)

+ H

2

O

(l)

 ???






N

2

O

5 (g)

+ H

2

O

(l)

 H

2

N

2

O

6

= 2HNO

3

Empirical formula



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



Remember  [H

2

O = H + OH ]

Examples of metal oxides include:

Copper (II) oxide

Aluminum oxide

Sodium oxide

CuO

Al

2

O

3

Na

2

O




(start with the metal and end with hydroxide,

OH )





OH )

Example: Sodium oxide reacts with water.





OH )


Na

2

O

(s)

+ H

2

O

( l )

 ???





OH )


Na

2

O

(s)

+ H

2

O

( l )

 2NaOH

(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



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

1 Beryllium metal reacts with oxygen gas

Be + O

2

 Be +2 + O -2  2BeO

Balanced, it looks like this…

2Be + O

2

 2BeO




2 Gaseous dinitrogen pentoxide reacts with water




2 Gaseous dinitrogen pentoxide reacts with water

N

2

O

5

+ H

2

O  H

2

N

2

O

6

= 2HNO

3

Empirical 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.

3N

2 (g)

+ 2S

(s)

 2N

3

S




4 Chunks of Calcium oxide is dropped into water




4 Chunks of Calcium oxide is dropped into water

CaO + H

2

O  Ca(OH)

2




5 Aluminum metal rusts




5 Aluminum metal rusts

Al + O

2

 Al +3 + O -2 

Balanced, it looks like this,

Al

2

O

3

4Al + 3O

2

 2Al

2

O

3



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 - Reeths

Section 8.2

Types of Chemical Reactions

predict their products.

…but it’s not balanced yet.

Now its your turn…

Practice Examples

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Section 8.2 Types of Chemical Reactions - Reeths

Section 8.2

Types of Chemical Reactions

predict their products.

…but it’s not balanced yet.

Now its your turn…

Practice Examples

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