Alkane Reactions Flashcards
hydrocarbons wherein all bonds around carbon atom are single bonds, that is, all the carbon are sp3 hybridized
alkane
all the bonds are sigma bonds, the geometry is tetrahedral, and the angle between the bonds is 109.5o
what type of hybridized carbons
Sp3
general formula for alkane, where n is any integer
CnH2n+2
ethane number of C and H atoms
C- 2
H - 6
alkanes are these thus the intermolecular force of attraction amongst the molecules is wander vaals and therefore the melting point and boiling point are relatively lower than other organic compounds of the same number of carbon atoms
nonpolar
The number of carbons ____ both the melting point and boiling point
increase
The increase of the length of the carbon chain _____ the surface area of molecules
increases
as the branching increases the melting point and the boiling point ____
decreases
most important sources of alkane
gas and petroleum
process to obtain alkanes from natural sources
distillation
set a systematic way of naming organic compounds (IUPAC)
Union of Pure and Applied Chemistry
set a systematic way of naming organic compounds (IUPAC)
Union of Pure and Applied Chemistry
identify the special branched constituents
grade yourself accordingly
reaction of alkane with molecular oxygen, O2. In the presence of heat to produce carbon dioxide, CO2, and water, H2O. The general equation is written as:
combustion
what will the alkane react with in a combustion reaction
oxygen
product of combustion reaction
CO2 + H2O
draw the products of alkanes in combustion reaction
grade yourself accordingly
three possible reactions of alkanes
combustion
cracking
halogenation
involves the breakdown of long chain alkanes to smaller chain alkanes with the use of high temperature or catalysts
cracking
two types of cracking
thermal cracking
catalytic cracking
carried out at a temperature of approximately 750oC and at a pressure of 70 atm
thermal cracking
temperature and pressure of alkane cracking
750 degrees
70 atm
Gives a mixture of products with a high proportion of hydrocarbons with carbon to carbon double bonds (alkenes)
thermal cracking
uses a zeolite catalyst that allows cracking to take place at a lower temperature (500oC) and pressure
catalytic cracking
chosen to give high percentages of hydrocarbons with between 5 and 10 carbon atoms
zeolites
zeolites give high percentage of hydrocarbons between how many carbon atoms
5 to 10
produces high proportions of branched alkanes and aromatic hydrocarbons such as benzene, which burn more evenly in car engines
catalytic cracking
alkane will react with Cl2 or Br2 in the presence of UV light to produce alkyl halide
free radical halogenation of alkane
form in the mechanism where alkyl halide were produced
free radicals
For halogenation reaction, the carbon atom must have a hydrogen atom attached to it, therefore a ____ substituted C will not undergo halogenation.
quaternary
three step of free radical halogenation
initiation
propagation
termination
involves the formation of free radical when UV light reacts with the halogen, X2 (the halogen may be Cl2 or Br2)
initiation
draw the initiation process of X2
check ppt for answer
involves the reaction of one halogen free radial to alkane to produce alkyl free radical and HX.
propagation
draw the propagation process
grade yourself accordingly
when the halogen free radical and the alkyl free radical reacts with each other, the alkyl halide is formed
termination
draw the termination process
grade yourself accordingly
do the reaction with CH4
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read the major product formation of alkane
grade yourself
initiation is what kind of reaction
endothermic
radical recombination is what kind of reaction
always exothermic
termination is what kind of reaction
always exothermic
propagation X=Br what kind of reaction
endothermic
X-Cl what kind of reaction
extohermic
