All Students Notes

Properties of Alkanes Physical Properties  Alkanes containing four carbon atoms (i.e. methane, ethane, propane and butane) are colorless, odorless gases. Alkanes containing five to seventeen carbons atoms are colorless , odorless liquids. Higher alkanes are also colorless, odorless solids. Chemical Properties Halogenation of Alkanes A reaction in which a hydrogen of alkane is replaced by a halogen atom is called halogenation.  In diffused Sunlight Halogenation takes place in the presence of diffused sunlight.  If halogen is present large quantity, this reaction continues to take place as follows. The chlorination of methane usually produce a mixture of products.  In Direct Sun light Reaction of methane with chlorine in direct sunlight is explosive and gives carbon and HCl. The halogens react with alkane with following reactivity order: F2 > Cl2 > Br2 > I2. Fluorine reacts explosive; Chlorine reacts slowly in dark at room temperature but rapidly in strong sun...

Question 1. Define hydrocarbons.  Answer. The organic compounds which contain only carbon and hydrogen are called hydrocarbons.  Question 2. What are alkanes? Answer. The saturated hydrocarbons which have all single bonds are called alkanes.  OR the hydrocarbons which have general formula CnH2n+2 are called alkanes. In alkanes, each carbon forms four single bonds and hydrogen forms one bond. For example, CH4, C2H6, C3H8 etc  Question. Draw structural formula of methane, ethane and propane. Solution Methane Ethane Propane For practice  Question  Draw structure of following compounds. 1. Butane 2. Pentane 3. Hexane 4. Heptane 5. Octane 6. Nonane 7. Decane Solution Question. Draw electron dot and cross structures for ethane. Solution Self-Assessment Exercise 12.2 Draw electron dot and cross structures for following.  a. Propane b. Butane Solution For practice  Question. Draw dot a...