Presentation2 (1).pptx about alksnes as fuells

part of organic

1. ALKALINES AS FUELS Nicole & Nissi

2. ALKANES The organic compounds having single-bonded carbon and hydrogen atoms are called alkanes. They have a homologous formula of CnH2n+2. It is further divided into chain alkanes, cycloalkanes, or branched alkanes. They have single covalent bonds in their structure. Alkanes are the simplest form of hydrocarbons with only carbon and hydrogen atoms. The simplest form has each carbon forming four different bonds with four hydrogen atoms. The simplest alkane is methane which is written as CH₄. The longest one is an octane with 8 carbon atoms with a molecular formula of C₈H₁₈. 

3. WHY ARE ALKANES EXCELLENT FUELS? Alkanes are saturated hydrocarbons, and they burn readily in the air with a blue non-sooty flame to release a lot of heat and light energy. This heat energy can be used for heating water, cooking food and operating machines in factories and generators in thermal power stations. That is why they are excellent fuels.

4. EXAMPLES of alkanes Methane-CH₄ Ethane – C₂H₆ gPropane – C₃H ₈ Butane – C₄H₁₀ Pentane- C₅H₁₂

5. Physical properties of alkanes The Boiling Point of Alkanes Since the intermolecular Van Der Waals force is directly proportional to molecular size and the surface area, we can see that the boiling point also increases in the same manner. Alkanes have a higher boiling point, especially the single-chain alkanes when compared to their isomers.  2 . The Melting Point of Alkanes The melting point of alkanes is also the same as their boiling point and increases with the molecular weight. The higher alkanes which are solid in nature, cannot overcome the intermolecular forces happening between them. So they are not easy to melt. Alkanes with even-numbered alkanes are more difficult to melt than odd-numbered ones. The former ones will have better packing of the components making it difficult to break them. 

6. U ses of alkanes Alkanes are the principal component in lubricants or oils. Methane and ethane are natural gasses used for cooking. The crude oil mainly consists of alkanes. Alkanes with a high number of carbon atoms are used as anti-corrosive agents.  Alkanes such as nonane and hexadecane are used in diesel, kerosene, aviation fuel etc.  Alkanes having 6-8 carbon atoms are volatile and are used as solvents for nonpolar solutions.  Propane and butane are used as liquified gas. 

7. W hy are alkanes used as fuels? Alkanes are used as fuel because there is the evolution of a large amount of heat during combustion use there is the evolution of a large amount of heat during combustion.

8. EXAMPLES Crude oil is an example of an alkane Crude oil  is a  finite  resource that is found in the Earth’s crust. It is the remains of  organisms  that lived and died millions of years ago - mainly plankton which was buried in mud. Crude oil is a complex  mixture  of hydrocarbons. The carbon atoms in these molecules are joined together in chains and rings. In the ball and stick models below, carbon atoms are black and hydrogen atoms are white.

9. GENERAL FORMULA The general formula for the alkanes is C n H 2n +2 , where n is the number of carbon atoms in the molecule. EXAMPLE Decane is an alkane. Its  molecules  contain 10 carbon  atoms . Predict the molecular formula of decane and explain your answer. The formula will be C 10 H 22 . This is because  n  = 10. So, 2 n  + 2 = (2 × 10) + 2 = 20 + 2 = 22.

10. TOPICALQUESTION Hexane is an alkane. Its molecules contain six carbon atoms. Predict the molecular formula of hexane.

11. T he answer; The formula will be C 6 H 14 .

12. THANK YOU