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Chemical reaction:It is a process that involves breaking the

existing bonds in the reactant molecules and forms new bonds in the products.

Importance of chemical reactions:1. Burning of car fuel in the car engine.2. Plants make their food through

photosynthesis process.3. Medicine, fertilizers, artificial fibers are

examples of outcomes of some chemical reactions.

Chemical Reaction

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1. Thermal decomposition reactions.2. Substitution reactions.3. Oxidation reduction reactions.

Types of chemical reactions

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First: Thermal decomposition reactions

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2 HgO 2Hg + O2

1. Thermal decomposition of mercuric oxide (HgO)

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Cu(OH)2 CuO + H2O blue black

2.Thermal decomposition of Copper hydroxide ( Cu (OH)2)

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CuCO3 CuO +CO2

Green black

3 2.Thermal decomposition of Copper carbonate (CuCO3)

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CuSO4 CuO + SO3

blue black

4.Thermal decomposition of copper sulphate(CuSO4)

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2NaNO3 2 NaNO2 + O2

5.Thermal decomposition of Sodium nitrate(NaNO3)

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Air bags:They are considered one of the most important safety means in cars at emergencies.

Science, Technology and society

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Answer ( Worksheet 1) in the science booklet page 12

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They are the reactions which depend on the activity of the metals , where the element which is more active substitutes (replaces) the less active one in its compounds.

The activity of metals can be determined by using the

“chemical activity series”

Second: Substitution reactions

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It is the arrangement of the metals in an descending order according to their chemical activity .

chemical activity series:

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chemical activity series

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1.Simple substitution reactions

2. Double substitution reactions

Types of Substitution reactions

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+ +Types of simple substitution reactionsA. Metal substitutes Hydrogen of acid or

water.B. Metal substitutes another metal in its salt

solution.

1.Simple substitution reactions

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2Na +2 H2O 2NaOH + H2

A.(1) : Metal substitutes Hydrogen of water.

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Zn + 2HCl ZnCl2 +H2

A (2) : Metal substitutes Hydrogen of HCl acid

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2Al + 6HCl 2AlCl3

+3H2

Cu + HCl No Reaction

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Mg + CuSO4 MgSO4 +Cu

B. Metal substitutes another metal in its salt solution.

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booklet page 13

Answer Worksheet(2)

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2. Double substitution reactions

+ +

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1. Reaction between acid and alkali ( Neutralization reaction)

2. Reaction between acid and salt. 3. Reaction between two salt solution.

Types of Double substitution reactions

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Acid + Alkali Salt + Water

HCl + NaOH NaCl + H2O

1. Reaction between acid and alkali ( Neutralization reaction)

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NaCO3 + 2HCl 2NaCl + H2O+CO2

3. Reaction between two salt solution.

NaCl +AgNO3 NaNO3 +AgCL

2. Reaction between acid and salt.