REACTIONS

Reaction Types

Single-replacement One element replaces a second element in

a compound

Cl2 + 2 NaBr 2 NaCl + Br2

Zn + H2SO4 ZnSO4 + H2

Refer to Table 11.2 on page 333

Reaction Types (cont)

Decomposition Single compound breaks down into 2 or

more simpler compounds

2 H2O 2 H2 + O2

CaCO3 CaO + CO2

Reaction Types (cont)

Combination 2 or more reactants form a single new

substance

Fe + S FeS

2CaO + 2 H2O 2 Ca(OH)2

Practice

Complete the worksheet in groups.

Have the first 5 equations completed by the end of class.

Reaction Types (cont)

Double-replacement Positive ions are exchanged between two

compounds Generally occur in aqueous solution and

produce a precipitate

AgNO3 + NaCl AgCl + NaNO3

2 NaOH + H2SO4 Na2SO4 + 2 H2O

Reaction Types (cont)

Combustion Element, or compound, reacts with oxygen,

producing heat Oxygen always involved as reactant

CH4 + 2 O2 CO2 + 2 H2O

C2H5OH + 3 O2 2 CO2 + 3 H2O

BALANCING CHEMICAL EQUATIONS

Example Bike Manufacturing

Frame + wheel + handlebar + pedal = bicycle Identify the components, how many are

needed? 1 frame, 2 wheels, 1 handlebar and 2 pedals

Skeleton equation: F + W + H + P = FW2HP2

Balanced? F + 2 W + H + 2 P = FW2HP2

http://youtu.be/QjVYz00-Kxc

Example

Equation IS balanced:

Process

Write the skeleton equation first Use coefficients to balance the equation

Law of Conservation of Mass Mass is conserved Atoms in products are the same as the

reactants, but rearranged

Practice

Zn + HCl ZnCl2 + H2

Zn + 2 HCl ZnCl2 + H2

C2H6 + O2 CO2 + H2O 2 C2H6 + 7 O2 4 CO2 + 6 H2O

BCE Practice

___ Al2O3 ___ Al + ___ O2

___ BaCl + ___ H2SO4 ___ BaSO + ___ HCl

___ CuCl2 + H2S ___ CuS + ___ HCl

Questions?

Summary

What is a coefficient? What are the on the left of the

chemical equation? On the right? Worksheet due tomorrow!!