Alkenes are not used as fuels because: They are scarce in nature. They are made from other hydrocarbons to make plastics, anti–freeze and many other useful compounds. They burn with a smoky flame due to less efficient, and more polluting incomplete combustion, so the heat energy release is lower than for alkanes.

To calculate how many hydrogen atoms an alkane has, double the number of carbons and add two. The general formula of the alkanes is….Alkanes.

The simplest alkane is methane. Methane contains only one carbon atom and four hydrogen atoms. The other alkanes can be made by substituting carbon atoms for hydrogens. The cycloalkanes are similar to the linear and branched alkanes, except that the carbon backbone has the carbon atoms arranged in a circle.

What are the first four alkanes? Methane (CH4), ethane (C2H6), propane (C3H8) and butane (C4H10) are the first four alkanes. Methane gas, whose molecular formula is CH4, is the simplest alkane.

tridecane

Since Alkanes are Saturated Hydrocarbons, they do not readily react. However, they can be made to react under certain conditions, so give useful products or energy output. Alkanes will react with Oxygen if they are given sufficient Activation Energy.

Smaller hydrocarbons make better fuels as they are easier to ignite. However, crude oil contains a lot of longer chain hydrocarbons. To break a longer chain hydrocarbon down into a smaller one we use a process known as cracking. Alkene A hydrocarbon that contains at least one carbon to carbon double bond.

Alkanes (the most basic of all organic compounds) undergo very few reactions. The two reactions of more importaces is combustion and halogenation, (i.e., substitution of a single hydrogen on the alkane for a single halogen) to form a haloalkane.

Alkenes (also called olefins) and alkynes (also called acetylenes) belong to the class of unsaturated aliphatic hydrocarbons. Alkenes are hydrocarbons that contain a carbon-carbon double bond, whereas alkynes have a carbon-carbon triple bond.

Because they have only strong σ bonds and atoms with no partial charges, alkanes are very unreactive compounds.

1 : lacking the power to move. 2 : very slow to move or act : sluggish. 3 : deficient in active properties especially : lacking a usual or anticipated chemical or biological action.

Alkanes are not soluble in water, which is highly polar. The two substances do not meet the criterion of solubility, namely, that “like dissolves like.” Water molecules are too strongly attracted to one another by hydrogen bonds to allow nonpolar alkanes to slip between them and dissolve.

Alkenes are relatively stable compounds, but are more reactive than alkanes because of the reactivity of the carbon–carbon π-bond. Because the carbon-carbon π bond is relatively weak, it is quite reactive and can be easily broken and reagents can be added to carbon.

The reason is that double bonds, especially when discussing carbon, are reactive is that breaking one double bond to make two single bonds results in lower energy. Breaking one C=C bond and one Cl-Cl bond loses 856 kJ/mol, but gaining a C-C bond and two Cl-Cl bonds gains 1004 kJ/mol.

The number of hydrogen atoms in an alkene is double the number of carbon atoms, so they have the general formula. Alkenes are unsaturated, meaning they contain a double bond . This bond is why the alkenes are more reactive than the alkanes .

The C=C bonds of alkenes are electron-rich and nucleophilic, in contrast to the electron-poor C=O. bonds of carbohydrates, fatty acids and proteins. Alkenes are reactive because they have a high-lying pair of π-bonding electrons. These electrons are loosely held, being high in energy compared to σ-bonds.

Electrophilic addition is probably the most common reaction of alkenes. Consider the electrophilic addition of H-Br to but-2-ene: The alkene abstracts a proton from the HBr, and a carbocation and bromide ion are generated. The bromide ion quickly attacks the cationic center and yields the final product.

3-methylpent-2-ene

Cycloalkanes are more toxic than alkanes or branched alkanes [878]. In humans, high concentrations of inhaled alkanes can result in anesthetic effects or narcosis [878]. Alkanes are CNS depressants [855]. However, high molecular weight alkanes are considered virtually non toxic [878].

Longer chain alkanes are typically more stable (relatively, based on the number of carbons) compared with a shorter chain alkane. More branched compounds are typically more stable than straight chain alkanes with the same number of atoms. For example, 2-methylpropane is more stable than butane.