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  4. Chemical Properties and Interchange Between Homologous Series

Chemical Properties and Interchange Between Homologous Series

 
2.3   Chemical Properties and Interconversion of Compounds between Homologous Series
 
Chemical Reactions of Alkanes
Combustion
  • Combustion of alkane involves the reaction of alkane with oxygen gas in the air.
  • Complete combustion of an alkane is when the oxygen gas is in excess.
  • The products of complete combustion of alkane are carbon dioxide gas and water.
  • Example of the complete combustion of methane:

\(CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l)\)

 

  • In the case of insufficiency of oxygen gas, the incomplete combustion of alkane occurs.
  • The products such as carbon monoxide and carbon might be formed from incomplete combustion of alkane.
  • Example of the incomplete combustion of methane;

\(2CH_4(g) + 3O_2(g) \rightarrow C(s)+CO_2(g) + 4H_2O(l)\)

or

\(6CH_4(g) + 9O_2(g) \rightarrow 2C(s)+2CO(g)+2CO_2(g) + 12H_2O(l)\)
Susbtitution Reaction
  • A chemical reaction where another atom is substituting one or more atoms in a molecule.
  • The substitution reaction of alkane that involves halogen is also called a halogenation reaction.
  • The sunlight is needed in this reaction.
  • The energy from the sunlight is needed to break the covalent bond in the halogen compound to form bond with halogen atoms.
  • Example of substitution reaction of methane with chlorin:

\(CH_4(g) + Cl_2(g) \rightarrow CH_2Cl_2(l) + H_2(g)\)
 
Chemical Reactions of Alkene
Combustion
  • Combustion of alkene involves the reaction of an alkene with oxygen gas in the air.
  • Complete combustion of an alkene is when the oxygen gas is in excess.
  • The products of complete combustion of alkene are carbon dioxide gas and water.
  • Example of the complete combustion of ethene:

\(C_2H_4(g) + 3O_2(g) \rightarrow 2CO_2(g)+ 2H_2O(l)\)

  • In the case of insufficiency of oxygen gas, the incomplete combustion of alkene occurs.
  • The products such as carbon monoxide and carbon might be formed from incomplete combustion of the alkene.
  • Example of the incomplete combustion of ethene:

\(C_2H_4(g) + O_2(g) \rightarrow 2C(p)+ 2H_2O(l)\)

atau

 

\(C_2H_4(g) + 2O_2(g) \rightarrow 2CO(g)+ 2H_2O(l)\)
Addition Reaction
  • Definition: a reaction where other atoms are added to a molecule.
  • The double bond in the alkene makes the compound reactive.
  • The addition reaction occurs at the double bond of the compound.
  • Five addition reactions that occur on alkenes is as stated below:

This image is an infographic titled ‘FIVE ADDITION REACTION THAT OCCUR ON ALKENES.’ It features a central light bulb icon with a check mark inside it, surrounded by five arrows pointing to different sections. Each section describes a type of addition reaction: 1. Addition of hydrogen (hydrogenation) 2. Addition of halogen (halogenation) 3. Addition of halogen halide 4. Addition of water (hydration) 5. Oxidation with acidified potassium manganate(VII), KMnO4 solution The image has a clean design with blue and red text and graphics on a white background. The Pandai logo is in the top left corner.

1. Addition of Halogen (Halogenation)
  • Reaction with halogen (chlorine, bromine) at room condition.
  • This reaction is also called the halogenation reaction.
  • Product: Haloalkane.

\(C_2H_4(g) + Cl_2(g) \rightarrow C_2H_4Cl_2(g)\)
2. Addition of Hydrogen (Hydrogenation)
  • Alkenes react with hydrogen at a temperature of 180 °C in the presence of nickel /platinum as a catalyst to produce the corresponding alkanes.
  • Catalyst: platinum, Pt or nickel, Ni.
  • Temperature: 180°C.
  • This reaction is also called a hydrogenation reaction.
  • Product: Alkane.

\(\, \\C_2H_4(g) + H_2(g) \xrightarrow []{Pt\,or\, Ni}C_2H_6(g)\)
 

 

 

 
3. Addition of Water (Hydration)
  • Alkenes react with water (in the form of steam) at high temperature and pressure, in the presence of phosphoric acid, H3 PO4 as a catalyst to produce alcohol.
  • Catalyst: phosphoric acid.
  • Temperature: 300°C.
  • Pressure: 60 atm.
  • This reaction is also called the hydration reaction.
  • Product: Alcohol.

\(\,\\C_2H_4(g) + H_2O(ce) \xrightarrow []{H_3PO_4}C_2H_5OH(ce)\)
4. Acidified potassium manganate(VII) solution, KMnO4
  • Acidified potassium manganate(VII) solution is a very good oxidising agent.
  • This reaction is also called the oxidation reaction.
  • Product: Diol (Alcohol with two hydroxyl groups).

\(C_2H_4(g) + H_2O(l) \xrightarrow []{[O]} CH_2OHCH_2OH(l)\)
Polymerisation Reaction
  • The pair of electrons making up one of the double bonds is shared with the carbon atom of another alkene molecule in the polymerisation reaction.
  • Example: polymerisation of ethene:
    • Polymer: polyethene.
    • Monomer: ethene.
    • Pressure: 2000 atm.
    • Temperature: 100°C to 300°C.
 
Penyediaan Etanol
Production of Ethanol in the Indutry
  • Addition reaction with water (steam)
    • Catalyst: phosphoric acid.
    • Temperature: 300°C.
    • Pressure: 60 atm.
  • \(C_2H_4(g) + H_2O(l) \xrightarrow[]{H_3PO_4} C_2H_5OH(l)\)
Production of Ethanol in the Laboratory
  • The fermentation process of carbohydrate or sugary substances like rice, barley or fruits
    • These substances contain glucose.
    • Zymase in yeast acts as a catalyst to convert glucose to ethanol. 
    • \(C_6H_{12}O_6(aq) \xrightarrow[]{yis} 2C_2H_5OH(l) + 2CO_2(g)\)
 
Chemical Properties of Ethanol
Combustion
  • Combustion of ethanol in excess oxygen produces carbon dioxide and water. 
  • \(C_2H_5OH(l) + 3O_2 (g) \rightarrow 2CO_2(g) + 3H_2O(l)\)
Oxidation
  • Ethanol is oxidised by acidified potassium dichromate(VI) solution.
  • Product: ethanoic acid
  • Dichromate ion (orange) changes to chromium ion (green). 
  • \(C_2H_5OH(l) \xrightarrow[]{[O]} CH_3COOH(l)\)
Dehydration
  • A water molecule is eliminated from the reaction.
  • Catalyst: sulphuric acid.
  • Temperature: 180°C.
  • Product: ethene.
  • \(C_2H_5OH(l) \xrightarrow[]{H_2SO_4, 180^\circ C} C_2H_4(g) + H_2O(l)\)
 
Preparation of Ethanoic Acid in the Laboratory
  • Oxidation of ethanol
    • Ethanol is oxidised by acidified potassium dichromate(VI) solution.
    • Dichromate ion (orange) changes to chromium ion (green). 
  • \(C_2H_5OH(l) \xrightarrow[]{[O]} CH_3COOH (l)\)
 
Chemical Reactions of Ethanoic Acid as An Acid
Reaction with Base or Alkali
  • Product: salt and water
  • Also known as neutralisation reaction.
  • Example of reaction with sodium hydroxide:
  • \(CH_3COOH (aq) + NaOH(aq) \rightarrow CH_3COONa (aq) + H_2O(l)\)
Reaction with Reactive Metal
  • Product: salt and hydrogen gas  
  • Example of reaction with magnesium:
  • \(2CH_3COOH (aq) + Mg(s) \rightarrow (CH_3COO)_2Mg (aq) + H_2(g)\)
Reaction with Metal Carbonate
  • Product: salt, carbon dioxide gas and water
  • Example of reaction with calcium carbonate:
  • \(2CH_3COOH (aq) + CaCO_3(s) \rightarrow (CH_3COO)_2Ca(aq) + H_2O(l) + CO_2(g)\)
 
The Chemical Reaction of Ethanoic Acid with An Alcohol
  • Product: ester.
  • Also known as an esterification reaction.
  • Catalyst: hydrogen ion.
  • \(CH_3COOH (aq) + C_2H_5OH(l) \xrightarrow []{H^+}CH_3COOC_2H_5(aq) + H_2O(l)\)
 
Ester
  • Functional group: carboxylate group,  \(-COOC-\)
  • General formula: \(C_nH_{2n+1}COOC_mH_{2m+1}\), where n = 0,1,2,… and m = 1,2,3,…
 
Naming Ester
  • Ester is produced by combining alcohol with carboxylic acid.
  • There are two parts to naming an ester.
  • The first part is based on the name of the alcohol.
  • The second part is based on the name of the carboxylic acid.
  • Example: Ethyl butanoate.

The diagram shows the structural formula of ethyl butanoate.
 
Steps in Naming An Ester
  1. Determine the alkyl group of the alcohol chain based on the structural formula or the molecular formula.
  2. Determine the name of the carboxylic acid part.
  3. Change the term ‘oic’ in carboxylic acid to ‘oate’.
 
Preparation of Ethyl Ethanoate in Laboratory
  • Mixing ethanoic acid with ethanol by reflux reaction.
  • Reflux is needed because ethanol is a volatile solution.
  • \(CH_3COOH(aq)+ C_2H_5OH(aq) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)
 
Physical Properties of Ethyl Ethanoate
  • A colourless solution at room temperature.
  • Nice fruity smell.
  • Soluble in water.
 
Esterification Ester
  • Product: ester.
  • Also known as an esterification reaction.
  • Catalyst: hydrogen ion.
  • Example of esterification reaction of ethanoic acid with ethanol:
  • \(CH_3COOH(aq)+ C_2H_5OH(aq) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)
 
This image is a diagram illustrating the various uses of esters. At the center, there is a box labeled ‘USES OF ESTER.’ Surrounding this central box are six other boxes connected by lines. Each of these boxes contains a different use of esters: 1. Explosives 2. Insect repellent 3. Detergent 4. Solvents 5. Perfumes 6. Food flavourings The background is white, and the boxes are in shades of blue. The diagram is branded with the ‘Pandai’ logo at the bottom right corner.
 
Natural Sources of Ester
Flower or Fruit Ester

Jasmie

 Benzyl ethanoate

Pear

 Propyl ethanoate

Apricot

 Pentyl propanoate

Kiwi

 Methyl benzoate

Pineapple

 Ethyl butanoate

Banana

 3-methylbutyl ethanoate
 

 

 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.

Chemical Properties and Interchange Between Homologous Series

 
2.3   Chemical Properties and Interconversion of Compounds between Homologous Series
 
Chemical Reactions of Alkanes
Combustion
  • Combustion of alkane involves the reaction of alkane with oxygen gas in the air.
  • Complete combustion of an alkane is when the oxygen gas is in excess.
  • The products of complete combustion of alkane are carbon dioxide gas and water.
  • Example of the complete combustion of methane:

\(CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l)\)

 

  • In the case of insufficiency of oxygen gas, the incomplete combustion of alkane occurs.
  • The products such as carbon monoxide and carbon might be formed from incomplete combustion of alkane.
  • Example of the incomplete combustion of methane;

\(2CH_4(g) + 3O_2(g) \rightarrow C(s)+CO_2(g) + 4H_2O(l)\)

or

\(6CH_4(g) + 9O_2(g) \rightarrow 2C(s)+2CO(g)+2CO_2(g) + 12H_2O(l)\)
Susbtitution Reaction
  • A chemical reaction where another atom is substituting one or more atoms in a molecule.
  • The substitution reaction of alkane that involves halogen is also called a halogenation reaction.
  • The sunlight is needed in this reaction.
  • The energy from the sunlight is needed to break the covalent bond in the halogen compound to form bond with halogen atoms.
  • Example of substitution reaction of methane with chlorin:

\(CH_4(g) + Cl_2(g) \rightarrow CH_2Cl_2(l) + H_2(g)\)
 
Chemical Reactions of Alkene
Combustion
  • Combustion of alkene involves the reaction of an alkene with oxygen gas in the air.
  • Complete combustion of an alkene is when the oxygen gas is in excess.
  • The products of complete combustion of alkene are carbon dioxide gas and water.
  • Example of the complete combustion of ethene:

\(C_2H_4(g) + 3O_2(g) \rightarrow 2CO_2(g)+ 2H_2O(l)\)

  • In the case of insufficiency of oxygen gas, the incomplete combustion of alkene occurs.
  • The products such as carbon monoxide and carbon might be formed from incomplete combustion of the alkene.
  • Example of the incomplete combustion of ethene:

\(C_2H_4(g) + O_2(g) \rightarrow 2C(p)+ 2H_2O(l)\)

atau

 

\(C_2H_4(g) + 2O_2(g) \rightarrow 2CO(g)+ 2H_2O(l)\)
Addition Reaction
  • Definition: a reaction where other atoms are added to a molecule.
  • The double bond in the alkene makes the compound reactive.
  • The addition reaction occurs at the double bond of the compound.
  • Five addition reactions that occur on alkenes is as stated below:

This image is an infographic titled ‘FIVE ADDITION REACTION THAT OCCUR ON ALKENES.’ It features a central light bulb icon with a check mark inside it, surrounded by five arrows pointing to different sections. Each section describes a type of addition reaction: 1. Addition of hydrogen (hydrogenation) 2. Addition of halogen (halogenation) 3. Addition of halogen halide 4. Addition of water (hydration) 5. Oxidation with acidified potassium manganate(VII), KMnO4 solution The image has a clean design with blue and red text and graphics on a white background. The Pandai logo is in the top left corner.

1. Addition of Halogen (Halogenation)
  • Reaction with halogen (chlorine, bromine) at room condition.
  • This reaction is also called the halogenation reaction.
  • Product: Haloalkane.

\(C_2H_4(g) + Cl_2(g) \rightarrow C_2H_4Cl_2(g)\)
2. Addition of Hydrogen (Hydrogenation)
  • Alkenes react with hydrogen at a temperature of 180 °C in the presence of nickel /platinum as a catalyst to produce the corresponding alkanes.
  • Catalyst: platinum, Pt or nickel, Ni.
  • Temperature: 180°C.
  • This reaction is also called a hydrogenation reaction.
  • Product: Alkane.

\(\, \\C_2H_4(g) + H_2(g) \xrightarrow []{Pt\,or\, Ni}C_2H_6(g)\)
 

 

 

 
3. Addition of Water (Hydration)
  • Alkenes react with water (in the form of steam) at high temperature and pressure, in the presence of phosphoric acid, H3 PO4 as a catalyst to produce alcohol.
  • Catalyst: phosphoric acid.
  • Temperature: 300°C.
  • Pressure: 60 atm.
  • This reaction is also called the hydration reaction.
  • Product: Alcohol.

\(\,\\C_2H_4(g) + H_2O(ce) \xrightarrow []{H_3PO_4}C_2H_5OH(ce)\)
4. Acidified potassium manganate(VII) solution, KMnO4
  • Acidified potassium manganate(VII) solution is a very good oxidising agent.
  • This reaction is also called the oxidation reaction.
  • Product: Diol (Alcohol with two hydroxyl groups).

\(C_2H_4(g) + H_2O(l) \xrightarrow []{[O]} CH_2OHCH_2OH(l)\)
Polymerisation Reaction
  • The pair of electrons making up one of the double bonds is shared with the carbon atom of another alkene molecule in the polymerisation reaction.
  • Example: polymerisation of ethene:
    • Polymer: polyethene.
    • Monomer: ethene.
    • Pressure: 2000 atm.
    • Temperature: 100°C to 300°C.
 
Penyediaan Etanol
Production of Ethanol in the Indutry
  • Addition reaction with water (steam)
    • Catalyst: phosphoric acid.
    • Temperature: 300°C.
    • Pressure: 60 atm.
  • \(C_2H_4(g) + H_2O(l) \xrightarrow[]{H_3PO_4} C_2H_5OH(l)\)
Production of Ethanol in the Laboratory
  • The fermentation process of carbohydrate or sugary substances like rice, barley or fruits
    • These substances contain glucose.
    • Zymase in yeast acts as a catalyst to convert glucose to ethanol. 
    • \(C_6H_{12}O_6(aq) \xrightarrow[]{yis} 2C_2H_5OH(l) + 2CO_2(g)\)
 
Chemical Properties of Ethanol
Combustion
  • Combustion of ethanol in excess oxygen produces carbon dioxide and water. 
  • \(C_2H_5OH(l) + 3O_2 (g) \rightarrow 2CO_2(g) + 3H_2O(l)\)
Oxidation
  • Ethanol is oxidised by acidified potassium dichromate(VI) solution.
  • Product: ethanoic acid
  • Dichromate ion (orange) changes to chromium ion (green). 
  • \(C_2H_5OH(l) \xrightarrow[]{[O]} CH_3COOH(l)\)
Dehydration
  • A water molecule is eliminated from the reaction.
  • Catalyst: sulphuric acid.
  • Temperature: 180°C.
  • Product: ethene.
  • \(C_2H_5OH(l) \xrightarrow[]{H_2SO_4, 180^\circ C} C_2H_4(g) + H_2O(l)\)
 
Preparation of Ethanoic Acid in the Laboratory
  • Oxidation of ethanol
    • Ethanol is oxidised by acidified potassium dichromate(VI) solution.
    • Dichromate ion (orange) changes to chromium ion (green). 
  • \(C_2H_5OH(l) \xrightarrow[]{[O]} CH_3COOH (l)\)
 
Chemical Reactions of Ethanoic Acid as An Acid
Reaction with Base or Alkali
  • Product: salt and water
  • Also known as neutralisation reaction.
  • Example of reaction with sodium hydroxide:
  • \(CH_3COOH (aq) + NaOH(aq) \rightarrow CH_3COONa (aq) + H_2O(l)\)
Reaction with Reactive Metal
  • Product: salt and hydrogen gas  
  • Example of reaction with magnesium:
  • \(2CH_3COOH (aq) + Mg(s) \rightarrow (CH_3COO)_2Mg (aq) + H_2(g)\)
Reaction with Metal Carbonate
  • Product: salt, carbon dioxide gas and water
  • Example of reaction with calcium carbonate:
  • \(2CH_3COOH (aq) + CaCO_3(s) \rightarrow (CH_3COO)_2Ca(aq) + H_2O(l) + CO_2(g)\)
 
The Chemical Reaction of Ethanoic Acid with An Alcohol
  • Product: ester.
  • Also known as an esterification reaction.
  • Catalyst: hydrogen ion.
  • \(CH_3COOH (aq) + C_2H_5OH(l) \xrightarrow []{H^+}CH_3COOC_2H_5(aq) + H_2O(l)\)
 
Ester
  • Functional group: carboxylate group,  \(-COOC-\)
  • General formula: \(C_nH_{2n+1}COOC_mH_{2m+1}\), where n = 0,1,2,… and m = 1,2,3,…
 
Naming Ester
  • Ester is produced by combining alcohol with carboxylic acid.
  • There are two parts to naming an ester.
  • The first part is based on the name of the alcohol.
  • The second part is based on the name of the carboxylic acid.
  • Example: Ethyl butanoate.

The diagram shows the structural formula of ethyl butanoate.
 
Steps in Naming An Ester
  1. Determine the alkyl group of the alcohol chain based on the structural formula or the molecular formula.
  2. Determine the name of the carboxylic acid part.
  3. Change the term ‘oic’ in carboxylic acid to ‘oate’.
 
Preparation of Ethyl Ethanoate in Laboratory
  • Mixing ethanoic acid with ethanol by reflux reaction.
  • Reflux is needed because ethanol is a volatile solution.
  • \(CH_3COOH(aq)+ C_2H_5OH(aq) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)
 
Physical Properties of Ethyl Ethanoate
  • A colourless solution at room temperature.
  • Nice fruity smell.
  • Soluble in water.
 
Esterification Ester
  • Product: ester.
  • Also known as an esterification reaction.
  • Catalyst: hydrogen ion.
  • Example of esterification reaction of ethanoic acid with ethanol:
  • \(CH_3COOH(aq)+ C_2H_5OH(aq) \xrightarrow[]{ H_2SO_4}  CH_3COOC_2H_5(aq)+H_2O(l)\)
 
This image is a diagram illustrating the various uses of esters. At the center, there is a box labeled ‘USES OF ESTER.’ Surrounding this central box are six other boxes connected by lines. Each of these boxes contains a different use of esters: 1. Explosives 2. Insect repellent 3. Detergent 4. Solvents 5. Perfumes 6. Food flavourings The background is white, and the boxes are in shades of blue. The diagram is branded with the ‘Pandai’ logo at the bottom right corner.
 
Natural Sources of Ester
Flower or Fruit Ester

Jasmie

 Benzyl ethanoate

Pear

 Propyl ethanoate

Apricot

 Pentyl propanoate

Kiwi

 Methyl benzoate

Pineapple

 Ethyl butanoate

Banana

 3-methylbutyl ethanoate
 

 

 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.
Chapter : Carbon Compounds
Topic : Chemical Properties and Interchange Between Homologous Series
Form 5 Chemistry
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