KEY NOTES – Chemical Properties -Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

KEY NOTES – Chemical Properties-Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

Chemical Properties of Carbon Compounds :

The chemical properties of carbon compounds are diverse and reflect the versatile nature of carbon in forming a wide range of molecules.

1. Combustion:

Reaction: Hydrocarbons react with oxygen to undergo combustion.

Result: Formation of carbon dioxide and water.

Example: Methane (CH4) combusts to form carbon dioxide (CO2) and water (H2O).

Oxidation:

Reaction: Oxidation of alcohols, aldehydes, or primary/secondary alkanes.

Result: Formation of products with a higher oxidation state.

Example: Ethanol (C2H5OH) oxidizes to form acetic acid (CH3COOH).

Substitution Reactions:

Reaction: Hydrogen atoms in alkanes can be replaced by other atoms or groups.

Result: Formation of a substituted alkane.

Example: Methane (CH4) undergoing substitution with chlorine to form chloromethane (CH3Cl).

Addition Reactions:

Reaction: Unsaturated hydrocarbons (alkenes and alkynes) undergo addition reactions.

Result: Atoms or groups of atoms are added to the carbon-carbon double or triple bonds.

Example: Ethene (C2H4) undergoes addition with bromine to form 1,2-dibromoethane.

 Important Carbon Compounds : Ethanol and Ethanoic Acid

Ethanol (C2H5OH):

Physical Properties:

State at Room Temperature: Ethanol is a colourless liquid at room temperature.

Odor and Taste: It has a characteristic pleasant odour and a slightly sweet taste.

Solubility: Ethanol is miscible with water in all proportions.

Boiling Point: The boiling point of ethanol is relatively low, making it volatile.

Density: Ethanol has a lower density compared to water.

Chemical Properties:

Combustibility: Ethanol is highly combustible, and it burns to produce carbon dioxide and water.

Equation: C₂ H₅OH + 3O₂ à 2CO₂ + 3H₂O

Reaction with Sodium: Reacts with sodium to liberate hydrogen gas, indicating its weakly acidic nature.

Equation: 2C₂HOH + 2Na à 2C₂H₅Ona +H₂

Ester Formation: Can react with carboxylic acids in the presence of acid to form esters.

Equation: C₂H₅OH + C₂ H5 COOH + C₂H₅COOCH₃ +H₂O

Uses of Ethanol :

In preparation of soap, cosmetics and medicines

In alcoholic beverages

As a laboratory reagent

 Ethanoic Acid (CH3COOH):

Physical Properties:

State at Room Temperature: Ethanoic acid is a colorless liquid at room temperature.

Odor: It has a pungent vinegar-like smell.

Solubility: Ethanoic acid is soluble in water.

Boiling Point:The boiling point is higher than that of ethanol.

Density: It has a higher density compared to water.

Chemical Properties:

Combustibility: Ethanoic acid is combustible but less so compared to ethanol.

Equation: CH₃ COOH +2O₂ à 2CO₂ + 2H₂ 0

Reaction with Bases: Reacts with bases to form salts and water in neutralization reactions.

Equation: CH₃ COOH +NaOH à CH₃COONa + H₂ 0

Esterification: Reacts with alcohols to form esters and water.

Equation: CH₃COOH + C₂H₅ OHà CH₃COO C₂H₅ + H₂ 0

Decomposition: Undergoes thermal decomposition to produce carbon dioxide and water.

Equation: 2CH₃COOH à 2CO₂ + 2H₂ 0

Uses of Ethanoic Acid (CH3COOH):

Food Preservative: Used as a preservative and acidity regulator in the food industry.

Condiment: Commonly known as vinegar when diluted, it is used as a condiment.

Cleaning Agent: Employed as a cleaning agent for various surfaces.

Dyeing and Textile Industry: Used in dyeing processes and as a mordant in the textile industry.

Soaps and Detergent

Soaps :

Soaps are potassium or sodium salts of a carboxylic acid having a long aliphatic chain attached to it.

They are surfactants (compounds that reduce the surface tension between a liquid and another substance) and therefore help in the emulsification of oils in water.

Soaps are generally prepared via the saponification of fats and oils.

The carboxylate end of the soap molecule is hydrophilic whereas the hydrocarbon tail is hydrophobic.

Detergents :

Detergents are the potassium or sodium salts of a long alkyl chain ending with a sulfonate group.

They are soluble in hard water.

This solubility is attributed to the fact that the sulfonate group does not attach itself to the ions present in hard water.

Commonly, anionic detergents such as alkyl benzene sulfonates are used for domestic purposes.