1. Types of Chemical Reactions
12/7/2018
Dr Seemal Jelani Chem-100

2. Learning Outcomes
Identify, give evidence for, predict products of, and classify the following types of chemical reactions:
1. Synthesis (combination)
2. Decomposition
3. Single Replacement
4. Double Replacement
5. Neutralization (acid/base)
6. Combustion
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Dr Seemal Jelani Chem-100

3. Vocabulary Synthesis Decomposition Neutralization Single displacement
Double displacement
Combustion
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Dr Seemal Jelani Chem-100

4. Chemical Reactions
A chemical change: any change in which a new substance is formed.
Evidence of a Chemical Change:
Release of energy as heat
Release of energy as light
Change in colour
Formation of a gas
Change in odour…
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Dr Seemal Jelani Chem-100

5. Types of Chemical Reactions
Neutralization: Acid(H) + Base(OH)  salt + H(OH)
Combustion: AB + oxygen  CO2 + H2O
Synthesis: A + B  AB
Decomposition: AB  A + B
Single displacement: A + BC  AC + B
Double displacement: AB + CD  AD + CB
12/7/2018
Dr Seemal Jelani Chem-100

6. Synthesis Reactions A + B  AB where A and B represent elements
Synthesis reactions are also known as FORMATION reactions.
Two or more reactants (usually elements) join to form a compound.
A + B  AB where A and B represent elements
The elements may form ionic compounds, like…
Sodium metal and chlorine gas combine to form sodium chloride.
2Na + Cl2  2NaCl
Sodium added to chlorine gas
See pages
12/7/2018
Dr Seemal Jelani Chem-100

7. Types: Synthesis General: A + B  AB Example C + O2  + O O O O O O O
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Dr Seemal Jelani Chem-100

8. SYNTHESIS REACTION (iron + sulphur):
Synthesis Reactions
OTHER EXAMPLES…
Elements that form ionic compounds:
Magnesium metal reacts with oxygen gas to form magnesium oxide.
2Mg + O2  2MgO
2. Elements that form covalent compounds:
Nitrogen gas and oxygen gas join to form dinitrogen monoxide.
2N2 + O2  2N2O
SYNTHESIS REACTION (iron + sulphur):
See pages
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Dr Seemal Jelani Chem-100

9. Decomposition Reactions
Decomposition reactions are the opposite of synthesis reactions.
A compounds breaks down into two or more products (often elements).
AB  A + B where A and B represent elements
1. Ionic compounds may decompose to produce elements, like the following:
Table salt, sodium chloride, can be broken down into sodium metal and chlorine gas by melting salt at 800ºC and running electricity through it.
2NaCl  2Na + Cl2
See page 260
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Dr Seemal Jelani Chem-100

10. Types: Decomposition General: AB  A + B Example: NaCl  + Cl Na Cl Na
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Dr Seemal Jelani Chem-100

11. Types: Decomposition General: AB  A + B Example 2HgO  + O Hg Hg O
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Dr Seemal Jelani Chem-100

12. Decomposition Reactions
2. Covalent compounds may decompose into elements, like the following:
By running electricity through water, the water molecules decompose into hydrogen and oxygen gases.
2H2O  2H2 + O2
DECOMPOSITION REACTION:
See page 260
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Dr Seemal Jelani Chem-100

13. Single Replacement Reactions
Single replacement reactions replace one element from a compound with another element.
A compound and an element react, and the element switches places with part of the original compound.
A + BC  B + AC where A is a metal, or
A + BC  C + BA where A is a non-metal
See page 261
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Dr Seemal Jelani Chem-100

14. Single Replacement Reactions
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Dr Seemal Jelani Chem-100

15. Types: Single displacement
Example: Zn + CuCl2  Zn Cl Cu + Cl Zn Cu +
General: AB + C  AC + B
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Dr Seemal Jelani Chem-100

16. Single Replacement Reactions
1. When A is a metal:
Aluminum foil in a solution of copper(II) chloride produces solid copper and aluminum chloride.
2Al + 3CuCl2  3Cu + 2AlCl3
2. When A is a non-metal:
When fluorine is bubbled through a sodium iodide solution, iodine and sodium fluoride are produced.
Fl2 + 2NaI  I2 + 2NaF
SINGLE REPLACEMENT:
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Dr Seemal Jelani Chem-100

17. Double Replacement Reactions
Double replacement reactions swap elements between 2 compounds that react together to form two new compounds.
Two compounds react, with elements switching places between the original compounds.
AB + CD  AD + CB
See page 262
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Dr Seemal Jelani Chem-100

18. Double Replacement Reactions
See page 262
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Dr Seemal Jelani Chem-100

19. Types: Double displacement
Example: MgO + CaS S O  Mg Ca + O S Mg Ca +
General: AB + CD  AD + CB
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Dr Seemal Jelani Chem-100

20. Double Replacement Reactions
Two solutions react to form a precipitate (solid) and another solution.
Ionic solution + ionic solution  ionic solution + ionic solid. AB + CD  AD + CB
When potassium chromate and silver nitrate react, they form a red precipitate, silver chromate, in a solution of potassium nitrate.
K2CrO4 + 2AgNO3  Ag2CrO4 + 2KNO3
silver chromate
DOUBLE REPLACEMENT:
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Dr Seemal Jelani Chem-100

21. Neutralization Reactions
Neutralization reactions occur when an acid (most compounds starting with H) and a base (most compounds ending in OH) react to form a salt and water.
Neutralization reactions are a type of double replacement.
Acid + base  salt + water
HX + MOH  MX + H2O
where X and M are elements
See page 263
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Dr Seemal Jelani Chem-100

22. Neutralization Reactions
1. Sulfuric acid is used to neutralize calcium hydroxide:
H2SO4 + Ca(OH) 2  CaSO4 + 2H2O
2. Phosphoric acid helps to neutralize the compounds that cause rust, such as iron(II) hydroxide.
H3PO4 + 3Fe(OH)2  Fe3(PO4)2 + 6H2O
NEUTRALIZATION:
See page 263
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Dr Seemal Jelani Chem-100

23. where X and Y represent integers
Combustion Reactions
Combustion reactions occur when a compound or element react with oxygen to release energy and produce an oxide.
Also sometimes referred to as hydrocarbon combustion.
CXHY + O2  CO2 + H2O
where X and Y represent integers
METHANOL + oxygen:
See page 264
12/7/2018
Dr Seemal Jelani Chem-100

24. Combustion Reactions
1. Natural gas (methane) is burned in furnaces to heat homes.
CH4 + O2  CO2 + 2H2O + energy
2. An acetylene torch is used to weld metals together.
2C2H2 + 5O2  4CO2 + 2H2O + energy
3. Carbohydrates like glucose combine with oxygen in our body to release energy.
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Acetylene torch
See page 264
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Dr Seemal Jelani Chem-100

25. SUMMARY OF REACTIONS Take the Section 6.1 Quiz
MOVIE TO REVIEW:
See page 265
Dr Seemal Jelani Chem-100
12/7/2018
Take the Section 6.1 Quiz