alkanes Flashcards
what are alkanes
alkanes are saturated hydrocarbons
they contain single bonds between 2 carbon atoms
what is the general formula for an alkane
Cn H2n+2
where n = number of carbon atoms
which alkane can also be called a greenhouse gas
Methane
WHAT type of reaction do alkanes undergo?
substitution reactions
this gas is also a saturated hydrocarbon
ethane
which reagent is used to distinguish between ethane and ethene
alkaline potassium permanganate solution
which forms chloroform(CHCl₃)on halogenation in the presence of sunlight
methane
what is the compound formed when ethene reacts with hydrogen
ethane
the conversion to ethyne to ethane is called ____
Hydrogenation
the conversion to ethene to ethane is called ____
Hydrogenation
_____burns with a non - luminous flame
methane
3 uses of methane
- -used as a domestic fuel
- -used in the manufacture of hydrogen and carbon monoxide
- -it is used in natural gas an alternative fuel in place of gasoline
what is pyrolysis
the process of decomposition of a hydrocarbon into elements on heating in the absence of air
Ch4 —-> C + 2H2
1000 degree celcius
what are the physical properties of ethane
- –> colourless and odourless gas
- —>vapour density is 1.5
- —>sparingly soluble in water
- —>soluble in organic solvents
what are the physical properties of methane
- –> it is lighter than air
- –>it is insoluble in water but soluble in organic solvents
- –>it is a colourless and odourless gas
what is halogenation
it involves the replacement of hydrogen atoms of methane with halogen atoms
how is ethane gas collected
downward displacement of water
define cracking
when a bigger hydrocarbon breaks into smaller fragments it is called cracking.
there are 2 types of cracking thermal and catalytic
define thermal cracking
thermal cracking is when alkanes are heated to high temperature in the absence of air
they decompose into a mixture of saturated and unsaturated hydrocarbons and hydrogens
Ch4 —> C + 2H2 (1000 celcius)
define catalytic cracking
catalytic cracking is when alkanes are treated with a catalyst in the absence of air
they decompose into a mixture of saturated and unsaturated hydrocarbons and hydrogens
C2H6 —> CH2 = CH2 + H2 (SiO2 - Al2O3)
3 uses of ethane
- —> used as an industrial fuel
- —> used in precipitation of ethyl chloride
- —> it is used in the preparation of ethanol, ethanal and ethanoic acid
________ is required for the reaction of ethane with chlorine
diffused sunlight
why is methane known as marsh gas
Methane is called Marsh Gas. Because it isproduced when vegetation decomposes naturally within some geographicalmarshes,swamps, andbogs.
direct iodination for methane is not carried
Iodine reacts with methane reversibly. When iodine reacts with methane, it gives iodomethane and hydrogen iodide which is a strong reducing agent and it can convert to iodomethane back to methane.
CH4 + I2 –> CH3I + HI
To overcome this difficulty iodination is carried out in the presence of strong oxidizing agents like HIO3 which oxidize HI formed during the reaction.
HIO3 + 5 H I —>3H2O + 𝒊2
