fuels +heats of reaction

hydrocarbon

a compound composed of hydrogen and carbon only

homogulous series

group of organic chemicals which have the same general formula or differ by a CH2 or have the same functional group

what is the general formula of alkanes

CnH2n+2

are alkanes a saturated or unsaturated compound

saturated

what shape are alkanes

tetrahedral

what is a saturated compound ?

a compound that only has single bonds

list the start of all compounds from 1 -9

meth , eth , prop, but , pent , hex , hept , oct , non , dec

physical properties of ALKANES

first four are gases ,higher are liquids , insoluable in water , soluable in non-polar solvents like cyclohexane

what are the uses of alkanes ?

used as fuels

chemical formula for methyl

CH3

what is an isomer

compounds with the same chemical formular but a different structural one

name 2 isomers of pentane

2-methylbutane , 2,2-diethylpropane

what is the general formula for ALKENES

CnH2n

are alkenes saturated or unsaturated compounds

unsaturated , carbon - carbon double bond

what shape are alkenes

planar

/what is an unsaturated compound ?

a compound that has atleast one carbon-carbon double or triple bond

what are the properties of alkenes

gases at room temp up to butene, larger molecules have higher boiling points , insoluble in water , soluble in nonpolar substances such as benzene

why do you disregard the first test tube of ethene gas?

displaced air

why is it important not to overheat the ethanol?

it may pass over the catalyst to quick not giving enough time for reaction to occur

what safety precation is specific to the preperation of ethene gas ?

must remove test tube from water trough before removing heat source to prevent suck back

properties of ethene gas

colourless with a sweet smell

outline the test for unsaturation in ethene gas

add bromine water ,stop and shake, bromine water changes from a red to colourless

what is the general formula of alkynes

CnH2n-2

are alkynes satuated or unsaturated compounds

usaturated ,

what are the uses of alkynes/ethyne

welding

properties of ethyne

a colourless gas with a sweet smell

descibe the flame of ethyne when combustion test is carried out

burns with a black sooty flame

what is an aliphatic compound?

a compound that consits of open chains of carbon atoms and closed chain compounds

what is an aromati compound?

contains a benzene ring

give an example of a aliphatic compound

cyclohexane

properties of benzene

unreactive despite double bonds , highly toxic and carcinogenic

define octane number

the tendency of a fuel to auto-ignite

name the reference hydracarbons and there octane number

heptane , 0

2,2,4 trimethylpetane , 100

name the factors affecting octane number

length of carbon chain , degree of branching , cyclic or straight

name the processes fuel under go to raise there octane number

isomerisation , catalytic cracking , dehydrocyclization , additon of oxygenates

isomerisation

changing straight chain alkanes into straight chain isomers

catalytic cracking

spliting of a long chain molecule by heat and catalyst

dehydrocyclization

using catalysts to change linear molecules into cyclic ones, and cyclic molecules into aromatic ones

name a by-product of catalytic cracking

an alkene

name a by-product of dehydrocyclization

hydrogen gas

3 examples of oxygenates

ethanol , methanol , mbte

why is lead no longer used a oxygenate ?

its toxic and poisons the catalyst in a car catalytic converter

define steam reforming of a natural gas

steam is reacted with a natural gas using a catalyst

define electrolysis of water

an electric current is passed through water

why is steam reforming and electrolysis of water not used

to expensive to be practical

way to produce hydrogen

steam reforming of natual gas and electrolysis of water

uses of hydrogen

used to produce ammonia , used to produce margarine , burned as a fuel because it environmentally friendly its only by-product being water

why is hydrogen difficult to store

forms a very explosive mixture with air, making it very difficult to store and transport