1.0 Summary
The The aim aim of this this exper experim imen entt is is to to syn synthe thesi size ze met methan hane, e, ethen ethene, e, and and eth ethyn ynee and and to to characterize the prepared methane, ethene, and ethyne. Hydrocarbons, which contain only of hydrogen and carbon, are divided into three classification which are aliphatic, aromatic, and alicyclic. For this experiment, the hydrocarbons involved are aliphatic. Aliphatic is defined as an open chains of single, double, or triple bonded carbon atoms, which are known as alkane, alkene and alkyne. The experiment started with the preparation and collection of ethane, ethene and ethyne gases into different test tubes for each gases. !n the reaction with bromine, ethene decolourized the brown colour of the bromine solution. Alkane will only react with the presence of light, while alkene and alkyne can react with or without the presence of sunlight. "hen the gases are reacted with potassium permanganate solution, only ethene and ethyne reacted because the double and triple bonds were oxidized to form alcohols and glycerol. !n the reaction with acidified potassium permanganate, methane shows no change in result, while ethene and ethyne changed the solution to light purple and brownish, because alkene and alkyne are unsaturated hydrocarbons which are oxidised when it was reacted.
2.0 Aim
The aim of this experiment to synthesize and characterize the prepared methane, ethane and ethyne.
3.0 Introduction
Hydrocarbon solvent are compound that consist only carbon and hydrogen atom which can be classified into aliphatic and aromatic solvent #$heremisinoff % Archer, &''(). According to Fernandes, &''* aliphatic is a straight chain hydrocarbon while aromatic is a cyclic hydrocarbon. +ost of aliphatic compound is highly flammable which they can be use as source a fuel. Aliphatic compound can be classified into two which are saturated and unsaturated hydrocarbon. aturated hydrocarbon is aliphatic hydrocarbons in which all the carbon-carbon bond are single bond while the unsaturated bond is aliphatic hydrocarbons in which carbon-carbon bond may be double or triple bond. The example of saturated aliphatic bond are alkane or paraffin while the example of unsaturated aliphatic bond are alkene and alkyne.
4.0
Theory
aturated Aliphatic Hydrocarbon Alkane is member of saturated aliphatic hydrocarbon with only single bonds between the atoms which can be either straight-chain or branched-chain. ne of alkane member is methane. +ethane is the most simplest alkane that contain one atom of carbon and four atoms of hydrogen. !n order to obtain methane by using reduction of any halogenated derivatives of alkane. This type of reaction involves the replacement of one or more atoms of halogen.
/0
reductio
H0
The methane will almost have no reaction in the dark after test with bromine in carbon tetrachloride. This is because the bromine colour is gradually discharged as the substitution reaction proceeds and hydrogen bromide #H1r) is evolved. !n order to test for H1r, H1r will dissolve in the moisture of breath and form a cloud of droplets.
2nsaturated Aliphatic Hydrocarbon Alkene and Alkyne are the member of saturated aliphatic hydrocarbon with double #for alkene) and triple #for alkyne) bond. 3thene is the one alkene member and it can be synthesize by using dehydration of alcohols using aluminium oxide as catalyst or dehydration of alcohols using an acid catalyst. #$hemwiki.ucdavis.edu, &'4() 5ehydration of alcohols using aluminium oxide as ca talyst6 Al& $H($H&H⟶($H&7$H&8H&
Two tests another can be carried for alkene and alkyne by dissolved in carbon tetrachloride6
a. 1romine, dissolved in carbon tetrachloride , adds rapidly to alkenes at room temperature to
form
(/H$
8
$H/
dibromides
/
1r &
H
H
C
C
Br
Br
R
3vidence for the reaction is the disappearance of the bromine colour, even in the dark with no evolution of hydrogen bromide
b. 1aeyer Test. Alkenes react with neutral permanganate solution to form glycols while Alkynes give positive 1aeyer Test for unsaturation with a9ueous potassium permanganate.
(
/
(/H$
OH
OH
C
C
H
H
$H/
8
R
&+n.:
8
& ;+n.:
8
:H&.
8
& ;.H
Dark Brown Precipitate
Purpl
7.0
Experimental Results
Test
bservation +ethane
3thane
3thyne
1ubbles are produced. $olourless solution remains unchanged.
The colourless solution turns chalky.
$olourless solution remains unchanged.
$olourless solution remains unchanged.
$olourless solution remains unchanged.
1ubbles are produced.
$olourless solution turned chalky and produced bubbles.
3T 4A 4
Tubes left in darkness
3T 41
&
Tubes left in a bright light
3T 4A % 41 (
1lowing across the mouth of each of the test tubes
3T &A
:
& ml of '.(= potassium permanganate solution
>urple colour solution of potassium permanganate remained unchanged.
>urple colour of potassium permanganate solution turn into dark purple.
>urple colour of potassium permanganate solution turned into dark brown with pungent smell and precipitate.
>urple solution of potassium permanganate turns into dark brown.
>urple colour of potassium permanganate solution remains unchanged.
>urple colour of potassium permanganate solution turns into light purple.
>urple colour of potassium permanganate solution turns into dark brown.
3T &1
4ml Alkaline potassium permanganate
3T &$
?
.0
&ml Acidified potassium permanganate solution
A!A"#SIS A!$ $IS%&SSI'!
4. "hat do @saturated and @unsaturated mean when applied to hydrocarbonsB Cive examples of a saturated and an unsaturated hydrocarbon.
AT2/AT35 HD5/$A/1< is a hydrocarbon in which carbon atoms are bonded with a single covalent bond only are called saturated. 3xamples of saturated hydrocarbons are +ethane, 3thane, and >ropane. The general formula for alkane or saturated hydrocarbon is $nH&n8&. 2<AT2/AT35 HD5/$A/1< is a hydrocarbon in which two carbon atoms are bonded with a double covalent bond or triple covalent bond is called unsaturated hydrocarbon. There are two types of unsaturated hydrocarbonsE alkenes and alkynes. A;3<3 is an unsaturated hydrocarbon in which two carbon atoms are bonded with a double covalent bond is called alkene. 3xamples of alkene6 3thene, >ropene, 1utene. The general formula is $nH&n. A;D<3 is an unsaturated hydrocarbon in which two carbon atoms are bonded with a triple covalent bond is called alkyne. 3xamples of alkyne6 3thyne, >ropyne, 1utyne. The general formula is $nH&n-&
&. Cive Five #) sources of methane. i( )ydroelectric dams* "hen a dam is built, the area behind the dam is flooded by water that can
no longer travel where it used to flow. That leaves a potentially huge amount of vegetable matter #plants and trees) that use to exist in the open air rotting beneath the surface of the water. /otting vegetation produces methane, and in normal situations that methane would escape into the atmosphere in incremental doses. 1ut the rotting plants behind a dam store up their methane in the mud. "hen the supply of water lowers behind a dam, all of that stored-up methane can suddenly be released. ii( Rice* /ice is grown in flooded fields, a situation that depletes the soil of oxygen. oils that are
anaerobic #lacking oxygen) allow the bacteria that produce methane from decomposing organic matter to thrive. ome of this methane then bubbles to the surface, but most of it is diffused back into the atmosphere through the rice plants themselves. iii(
Semiconductors* the semiconductors in computers and mobile devices are produced using
several different methane gases, including trifluoromethane, perfluoromethane and perfluoroethane. ome of this gas escapes in the waste process. i+(
%ompostin,* Home or business composting is a great way to get rid of organic waste such
as yard trimmings and food scraps and transform them into something useful. 1ut itGs not without its downside6 The act of composting produces both carbon dioxide and methane. +(
'cean micro-es* As much as : percent of the planetGs methane comes from the ocean.
According to scientists from the 2niversity of !llinois and !nstitute for Cenomic 1iology, the ocean-based microbe Nitrosopumilus maritimus produces methane through a complex biochemical process the researchers referred to as weird chemistry. !t was a totally unexpected discovery that all other microbes known to produce methane canGt tolerate oxygen, which is found in both the air and water. (. 5escribe reactions that are characteristics of alkanes, alkenes and alkynes.
Alanes - Alkanes considered difficult substances react so-called paraffin which means little
affinity. The most important reaction of alkanes is combustion reactions, substitution and cracking.
i)
$ombustion
$omplete combustion of alkanes to produce gas $ & and water vapor, while the incomplete combustion produces $ gas and water vapor, or soot #carbon particles). ii) ubstitution Atom H from alkanes can be replaced by other atoms, especially the halogen group. /eplacement H atom by atom or another group called substitution reaction. ne of the most important substitution reactions of alkanes are halogenated alkanes, namely the replacement of H atoms by halogen atoms, especially chlorine. $hlorination can occur if the alkane is reacted with chlorine.
iii) $racking $racking is breaking the carbon chains into pieces shorter. !t can occur when the alkane is heated at high temperature and high pressure without oxygen. This reaction can also be used to make alkenes from alkanes. !t can also be used to create hydrogen gas from alkanes.
Alenes -alkenes more reactive than alkanes. This is because the double bond $ 7 $. Alkene
reactions mainly occur at the double bond. !mportant reactions of alkenes include6 co mbustion reactions, addition and polymerization. i)
$ombustion As with alkanes, alkenes low interest flammable. !f burned in the open air, alkenes produce more soot than alkanes. This happens because the alkene have higher levels of $ than alkanes, so that combustion demands I needs more oxygen.
ii)
Addition The most important reactions of alkenes are addition reactions that bond saturation reactions.
iii) >olymerization The
reaction
of
incorporation
of
simple.
+olecules
into
large
molecules.
imple molecules called monomers undergo polymerization, while the result is called a polymer. Alynes - These reactions are similar to the alkyne alkeneE to saturate double bonds, re9uiring
alkyne reagent & times more than the alkene. The most important reactions of alkenes and alkynes are addition reactions with H &, the addition of the halogen #0 &) and the addition of the acid halide #H0). !n addition reaction gas H0 #0 7 $l, 1r or !) to alkenes and alkynes +arkovnikov rules apply, namely6 J!f the $ atom bonded dual binding of different amounts of H atoms, the atom 0 will be bound to the atom $ a few atoms bind HK. !f the $ atom bonded to duplicate the number of H atoms bind together a lot, then the atom 0 will be bound to $ atoms that have the most long-chain $ :. "rite a balance e9uation for the reaction which methane was obtained by the reduction of chloroform. $H$l( 8 (H& L $H: 8 (H$l
.
>rovide & #T") other methods of collecting gas that can be used in this experiment.
i)A method for preparing and collecting a gas less dense #lighter) than air by heating solid reactants. The less dense gas rises into, and displaces, the more dense air downwards. This method of gas preparation is called upward delivery. +ethod for preparing and collecting a gas more dense #heavier) than air by heating the
ii)
reactants. The more dense gas sinks down into, and displaces, the less dense air upwards. This method of gas preparation is called downward delivery. /.0
%onclusion
The purpose of the experiment is to prepare and characterize methane, ethene, and ethyne gases. Throughout the experiment, we can conclude that in the reaction with bromine solution, each of the hydrocarbons will react. Alkane can only react with the presence of light, while alkene and alkyne can react in the presence or absence of light. !n the reaction with potassium
permanganate solution and acidified potassium permanganate solution, only ethene and ethyne reacted. There were few possible errors that occurred during the experiment. Firstly, the gases collected in the test tubes were expelled to the air when the stopper was pushed out of the mouth of the test tubes due to pressure.
