I II III IV V

Ch. 8 – Chemical Reactions

III. Types of Chemical Reactions

(p. 256 - 267)

1. Combustion

CH4(g) + 2O2(g) CO2(g) + 2H2O(g)

the burning of any substance in O2 to produce heat

A + O2 B

C3H8(g)+ O2(g) 5 3 4

1. Combustion

Reactants:

contain oxygen

Products: hydrocarbons form CO2 + H2O

CO2(g)+ H2O(g)

2. Synthesis

the combination of 2 or more substances to form a compound

only one product

A + B AB

Al(s)+ Cl2(g)

AlCl3(s)2 3 2

2. Synthesis Products:

ionic - cancel charges Reactants with O2 or S, products are oxides or sulfides

Reactants with oxides and groups 1 or 2 metals, products are hydroxides

SYNTHESIS

In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make one

product, a fat bird

2. Synthesis

Example C + O2 CO2

OO C +

OO COO C OO C OO C OO

C OO

C OO

CO

O

C O

O

C O

O

C OO

COO

COO C

OO C

General: A + B AB

B. Synthesis

H2(g) + Cl2(g) 2 HCl(g)

3. Decomposition

a compound breaks down into 2 or more simpler substances

only one reactant

AB A + B

KBr(l) K(s) + Br2(l) 2 2

3. Decomposition Products:

binary - break into elements Metal carbonates – metal oxides and CO2(g)

Metal hydroxides – EXCEPT Grp 1, metal oxides and H2O

Metal chlorides- chlorides and O2(g)

DECOMPOSITION

In this cartoon the egg (the reactant), which contained the turtle at one time, now has

opened and the turtle (product) and egg shell (product) are now two separate substances.

3. Decomposition

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

3. Decomposition

Example: NaCl

General: AB A + B

Cl Na Cl + Na

3. Decomposition

Example 2 HgO

O Hg

O Hg

Hg

O O Hg

+

General: AB A + B

4. Single Replacement

one element replaces another in a compound metal replaces metal (+) nonmetal replaces nonmetal (-)

A + BC B + AC

4. Single Replacement

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

Fe(s)+ CuSO4(aq) Cu(s)+ FeSO4(aq)

D. Single Replacement Products:

free element must be more active (check activity series) Metal in H2O – Group 1: hydroxides

and H2(g). All others: oxides and H2(g)

Metal in acid – salt and H2(g)

Br2(l)+ NaCl(aq) N.R.

SINGLE REPLACEMENT

Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the

reactants trades places and is in a different place among the products.

4. Single displacement

Example: Zn + CuCl2

ZnClCl Cu +

General: AB + C AC + B

ClCl Zn Cu+

AB + CD AD + CB

5. Double Replacement

ions in two compounds “change partners” cation of one compound combines with

anion of the other

Pb(NO3)2(aq)+ KI(aq) PbI2(s)+ KNO3(aq)

5. Double Replacement

Products: switch negative ions one product must be insoluble (check

solubility table)

NaNO3(aq)+ KI(aq) N.R.

2 2

5. Double displacement

Example: MgO + CaS

General: AB + CD AD + CB

SOMg Ca

+O S

Mg Ca+

5. Double Replacement

Pb(NO3)2(aq) + K2CrO4(aq) PbCrO4(s) + 2KNO3(aq)

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