Title: CHEMICAL REACTIONS
1CHEMICAL REACTIONS
- A chemical reaction can be observed or has taken
place when - a) a gas is given off
- b) a precipitate is formed
- c) change of color
- d) change in energy ( this could be manifested
as light or heat)
2- Classification of Chemical Equations
- Chemical equations can be classified into six
simple types - combination reactions
- decomposition reactions
- single replacement reactions
- d) double replacement reactions
- neutralization reactions
- oxidation-reduction reactions
- f) combustion reactions
3- Examples of decomposition reactions
- The general form is compound element
element -
- 2H2O 2H2 O2
- H2CO3 H2O CO2
4Combination reactions - two or more substances
(either elements or compounds) react to produce
one substance. These reactions are also called
synthesis reactions. A
B ---gt AB
2 Mg O2 ---gt 2 MgO C O2 (excess) ---gt
CO2 H2O MgO ---gt Mg(OH)2 2 Na Cl2 ---gt 2
NaCl
5Combination Reactions
6- Examples
- The general form is
- element compound compound element
- Zn 2HCl ZnCl2 H2
- 2Na 2H2O 2NaOH H2
7- Examples of double displacement reactions
- The general form is compound compound
compound compound - 2KCl Pb(NO3)2 2KNO3 PbCl2
8Double displacement reactions
9Neutralization reaction - the reaction of an acid
with a base to produce salt and water.
HCl NaOH ---gt NaCl H2O
- Examples of combustion reactions
- The general form is hydrocarbon oxygen
carbon dioxide water - CH4 2O2 CO2 2H2O
- C7H16 11O2 7CO2 8H2O
10The reaction between methane and oxygen.
11Oxidation-Reduction reactions - chemical
reactions in which a transfer of electrons occur
are classified as oxidation-reduction reaction or
redox reaction. Na(s) 1/2 Cl2 (g) ----gt
NaCl(s)
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