C11 Organic Chemistry

What is organic chemistry?

the study of the structure, properties, composition, reactions and preparation of carbon-containing compounds

What is a functional group?

an atom or group of atoms that determine the chemical properties of a homologous series

What is a homologous series?

a family of similar compounds with similar chemical properties due to the presence of the same functional group

What are the general characteristics of a homologous series?

-having the same general formula

-displaying a trend in physical properties

What is a saturated compound?

has molecules in which all carbon–carbon bonds are single bonds

What is a unsaturated compound?

has molecules in which one or more carbon–carbon bonds are not single bonds

What is the displayed formula?

shows all the atoms of each element and all the bonds in the molecule

Draw the displayed formula of methane (CH₄) +state what type it is

alkane

Draw the displayed formula of ethane (C₂H₆) +state what type it is

alkane

Draw the displayed formula of ethene (C₂H₄) +state what type it is

alkene

Draw the displayed formula of ethanol (C₂H₅0H) +state what type it is

alcohol

Name these compounds for the displayed formula

What is the compound present when chemical name ends with -ane?

alkane

What is the compound present when chemical name ends with -ene?

alkene

What is the compound present when chemical name ends with -ol?

alcohol

General formula for alkanes

C_nH_2n+2

General formula for alkenes

C_nH_2n

General formula for alcohol

C_nH_2n+1OH

Fill in this table for naming alkanes

What are the 4 rules to remember when drawing the displayed formula for alkane?

-there are only single carbon-carbon bonds

-carbon atoms must have 4 bonds

-hydrogen atoms must have 1 bond

-if there are side groups, attach to the correct carbon as numbered in the name

Fill in this table for naming alkenes

What is the difference between but-1-ene and but-2-ene?

but-1-ene has the double carbon bond between carbon 1 and carbon 2 while

but-2-ene has the double carbon bond between carbon 2 and carbon 3

Fill in this table for naming alcohols

Name the 3 main fossil fuels

coal, natural gas and petroleum

What is the main constituent of natural gas?

methane

What are hydrocarbons?

compounds that contain hydrogen and carbon only

What is petroleum?

a mixture of hydrocarbons

How is petroleum separated into useful fractions?

by fractional distillation which is where compounds are separated into its constituent substances based on their differences

Describe the process of petroleum seperation from fractional distillation

-petroleum is heated in a furnace until its vaporised and is added to a fractionating column that has divisions at different levels to collect the various constituents/fractions

-fractions will separate into its constituent levels based on their different properties: different boiling points, chain length, volatility and viscosity

Describe how the properties of fractions obtained from petroleum change from the bottom to the top of the fractionating column from decreasing chain length

-fractions with shorter carbon chains, such as propane, will be tapped from the top of the fractionating column.

-fractions with longer chain lengths will collect at the bottom of the fractionating column.

Describe how the properties of fractions obtained from petroleum change from the bottom to the top of the fractionating column from higher volatility

-fractions with higher volatility will separate off at the top of the fractionating

column

-fractions with lower volatility will collect at the bottom of the fractionating column

Describe how the properties of fractions obtained from petroleum change from the bottom to the top of the fractionating column from lower boiling points

-fractions with lower boiling points condense at higher levels (top of the

column)

-fractions with higher boiling points condense at lower levels (bottom of the

column)

Describe how the properties of fractions obtained from petroleum change from the bottom to the top of the fractionating column from lower viscosity

viscosity refers to how thick and sticky and substance is

-hydrocarbons with lower viscosity, such as refinery gases, will separate off at the top of the column

-hydrocarbons with higher viscosity, such as bitumen will collect at the bottom of the fractionating column

Name all the types of fractions collected and what is each used in [8]

Refinery gas fraction- Gas used in heating and cooking

Gasoline/petrol fraction- Fuel used in cars

Naphtha fraction- Used as a chemical feedstock

Kerosene /paraffin fraction- Used for jet fuel

Diesel oil/ gas oil fraction- Fuel used in diesel engines

Fuel oil fraction- Fuel used in ships and home heating systems

Lubricating oil fraction- Used for lubricants, waxes and polishes

Bitumen fraction- Used for making roads

What are alkanes?

saturated hydrocarbons, meaning they only consist of single bonds and have only hydrogen and carbon atoms

What is the bond in alkanes like?

all bonds are single covalent bonds

What are the properties of alkanes?

generally unreactive unless in combustion/burning

What are alkenes?

unsaturated hydrocarbons, meaning they consist of at least one double bond and have only hydrogen and carbon atoms

What is the bond in alkenes like?

has at least one double carbon–carbon covalent bond

How does the manufacture of alkenes and hydrogen happen?

manufactured by cracking long chain of larger alkanes molecules using a high temperature and a catalyst

-long chain hydrocarbons are heated until vaporised. The vapours are either passed over a hot catalyst to break the long chains or are mixed with steam at very high temperatures so that thermal decomposition occurs.

-cracking of long chain alkanes produces alkenes, shorter chain alkanes andhydrogen

What is the reason for the cracking of larger alkane molecules?

-Produces alkenes which can be used as chemical feedstock

-Helps to meet supply and demand of fractions

How to distinguish between saturated and unsaturated hydrocarbons?

to test for the presence of a double bond (whether a molecule is

unsaturated), add aqueous bromine

-there will be a colour change from orange to colourless

-in saturated compounds, aqueous bromine will remain orange

Describe the properties of alkenes in terms of addition reactions with bromine

alkenes will react with aqueous bromine and decolourise it from orange to colourless.

-this is because the double bond is more reactive than a single covalent bond and will react with bromine to form a dibromoalkane.

E.g. reaction between ethene and bromine.

Ethene + Bromine → 1,2-dibromoethane

C₂H₄ + Br₂ → C₂H₄Br₂

Describe the properties of alkenes in terms of addition reactions with hydrogen in the presence of a nickel catalyst

alkenes will react with hydrogen in an addition reaction to produce an alkane, by replacing the double carbon-carbon bonds with single covalent bonds.

E.g. reaction between propene and hydrogen, in the presence of a nickel catalyst.

Propene + Hydrogen → Propane

C₃H₆ + H₂ → C₃H₈

Describe the properties of alkenes in terms of addition reactions with

alkenes will react with steam in an addition reaction to produce an alcohol, replacing the double carbon-carbon bond with a hydroxyl group (-OH) and a hydrogen atom

E.g. reaction between ethene and steam, in the presence of an acid catalyst.

Ethene + Steam → Ethanol

C₂H₄ + H₂O → C₂H₅OH

How does combustion in ethanol work?

ethanol can be burnt in air or oxygen (complete combustion) to produce carbon dioxide and water?

What is balanced chemical equation for the complete combustion of ethanol?

C₂H₄OH + 3O₂ → 2CO₂ + 3H₂O

Why do we combust ethanol?

ethanol releases a lot of energy when burnt

What is the use of ethanol?

a solvent and a fuel

What are polymers?

large molecules built up from many smaller molecules called monomers