POINTS TO REMEMBER-Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

POINTS TO REMEMBER-Class 10 – Science -Chemistry -Chapter 4 – Carbon and its Compounds

POINTS TO REMEMBER

Carbon always forms covalent bonds.

Carbon is present in all substances of animal and vegetable origin 

The ability of carbon to unite with an indefinite number of carbon atoms in straight, branched or cyclic chains is known as catenation.

Caron and hydrogen combine together indifferent proportions to form a large number of compounds called hydrocarbons.

There are two types of hydrocarbonssaturated and unsaturated

Alkanes are represented by the general formula CnH2n +2

Alkenes are represented by the general formula CnH2n 

Alkynes are represented by the general formula CnH2n–2

Organic compounds having the same functional group and common properties, but differing in molecular formula from the next member by one CH2 group, form a homologous series and such compounds are called homologues.

Compounds with the same molecular formula but different structural formulae are known as isomers.

The decomposition of alkanes on heating in the absence of oxygen is known as cracking.

Methane is prepared by heating a mixture of sodium acetate and soda lime.

When ethanol is heated with an excess of concentrated sulphuric acid at 160°C, ethene gas is produced.

Natural gas is a mixture of gaseous hydrocarbons, mainly methane, ethane, propane and butane.

Compressed Natural Gas (CNG) is used as an alternative to petrol as automobile fuel.

Natural gas is a rich source of hydrogen gas which is required for the manufacture of fertilizers 

Liquefied Petroleum Gas (LPG) is used as a domestic fuel.

Petrol is a complex mixture of hydrocarbons such as hexane, heptane and octane. 

Petrol is used as a motor fuel.

Alcohols are organic compounds which contain hydroxyl group (–OH) bonded to a carbon atom.

Alcohols are neutral to litmus.

Alcohols are poor conductors of electricity.

Alcohol reacts with sodium to liberate hydrogen gas. 

Ethanol is a constituent of beverages, like wine and beer. 

Ethanol is used as a hypnotic and is highly addictive.

Organic compounds containing carboxyl group (–COOH) are called carboxylic acids.

Ethanoic acid reacts with sodium carbonate to produce carbon dioxide gas.

A dilute aqueous solution 4 – 6% of ethanoic acid is called vinegar

A 99% pure solution of acetic acid is called glacial acetic acid. 

A soap is a sodium or potassium salt of a long-chain carboxylic acid. Sodium palmitate, sodium stearate, etc., are examples of soaps.

The process of splitting fats or oils using alkalis is called saponification.

Soaps do not work well with hard water, but synthetic detergents do. 

Soaps are biodegradable, but synthetic detergents are not.