C13.1-3 Organic general concepts

What is a hydrocarbon

Compound consisting of C and H only

Principal source of hydrocarbons

Crude oil

Crude oil

Mixture of many hydrocarbons

How is crude oil first refined

Fractional distillation

How does temp of fractionating column vary

How at bottom, cool at tom

Each fraction after refining crude oil consists of

Hydrocarbons with similar boiling points

Larger hydrocarbons have … boiling points

Higher

Larger hydrocarbons are … viscous

More

Larger hydrocarbons are … flammable

Less

What is catalytic cracking

Longer chain molecules passed over heated catalyst , broken down to shorter chain molecules

Are the hydrocarbons before cracking alkanes or alkenes

Alkanes

Are the products of cracking alkanes or alkenes

Both

Can you predict the products of cracking a hydrocarbon molecule

No - random events

What is an alkane

Saturated hydrocarbon

What is an allele

Unsaturated hydrocarbon

What is a saturated hydrocarbon

No double C=C bonds

What is an unsaturated hydrocarbon

Contains C=C double bonds

Why is cracking useful

More demand for smaller hydrocarbons

Are alkanes or alkenes more reactive

Alkenes

How to test for C=C double bond

Bromine water turns from orange to colourless

Do alkenes or alkanes react with bromine water

Alkenes

Molecular formula of butane

C4H10

General formula for alkane

C (n) H (2n+2)

General formula for alkene

C (n) H (2n)

Condensed structural formula of butane

CH3 (CH2)2 CH3

What are structural isomers

Same molecular formula, different structural formula

Complete combustion of hydrocarbon requires

Excess of oxygen

Products of complete combustion of hydrocarbons

CO2 and water

How many molecules of CO2 are formed in complete combustion of hydrocarbon

Number of C atoms in hydrocarbon

How many molecules of water are formed in complete combustion of hydrocarbon

Half the number of H atoms in hydrocarbon

What are products of incomplete combustion of hydrocarbons

Depends - C/ CO/ CO2 + H2O

When balancing combustion equations can you leave decimal numbers

Yes

Methane molecular formula

CH4

Ethane molecular formula

C2H6

What is used to prefix a hydrocarbon

Longest straight chain of carbon atoms

Propane formula

C3H8

Butane formula

C4H10

Heptane formula

C7H16

Propene formula (1 double bond)

C3H6

Butene formula

C4H8

Methyl group formula

CH3

Ethyl group

C2H5

How are carbon atoms in the longest chain numbered

Such that position of branches are on the lowest number

2,3-dimethylhexane formula

CH3CH(CH3)CH(CH3)CH2CH2CH

If there is an ethyl and a methyl group which one comes first in the name

Ethyl (even if it is on a higher C atom)

What is a homologous series

Series of organic compounds w similar chemical properties + same general formula

Why do members of homologous series have similar chemical properties

Share same functional group

What is a functional group

Reactive part of the molecule

How to name an alkene (position of double bond)

Alk-n-ene (n should be lowest possible)

Alkene with two double bonds suffix

Diene

Pent-1,2-diene formula

CH2CCHCH2CH3

How many bonds must each carbon atom make

4

What happens in addition reactions of alkenes

Double bond opens up to allow each C to make another bond

Is the product of an addition reaction saturated or unsaturated

Saturated (bc double bond opens up)

Ethene + H2 →

Ethane

Ethene + Br2 reaction

Dibromoethane

Ethene + HCl

Chloroethane

Ethene + steam (H2O) →

Ethanol

How is water added across the double bond in ethene reaction w steam

H goes to one C atom and OH goes to the other

Colour of 1,2-dibromoethene

Colourless

What kind of reaction is the reaction of bromine water with ethene gas

Addition

What state are pentene and hexene at rtp

Liquid

Reaction of bromine water with alkane

None