[C7] Organic chemistry

What is crude oil?

a mixture of a large number of compounds, most of which are hydrocarbons

How was crude oil formed?

from the remains of organisms that lived and died millions of years ago (mainly plankton which was buried in the mud)

Is crude oil a finite or renewable resource?

Finite

What is a hydrocarbon?

a compound made up of carbon and hydrogen only

Why type of bond joins the carbon and hydrogen atoms in a hydrocarbon

covalent bond

What is an organic compound?

compounds containing carbon atoms covalently bonded to other atoms

What is a homologous series?

a family of organic compounds with the same general formula and similar properities

What is the general formula for alkanes?

CₙH₂ₙ₊₂

What are the names of the first four members of the alkanes?

Methane Ethane Propane Butane

What do the names of alkanes always end in?

-ane

How many bonds does carbon form in a compound?

four

How many bonds does hydrogen form in a compound?

one

How are the different compounds in crude oil separated?

Fractional distillation

What is a fraction?

a mixture of hydrocarbons with a similar number of carbon atoms

What are the products of fractional distillation used for?

• fuels • starting materials for the petrochemical industry

What are the names of some fractions produced in fractional disillation?

• petrol • diesel oil • kerosene • heavy fuel oil • liquefied petroleum gases

What useful materials are produced by the petrochemical industry?

• solvents • lubricants • polymers • detergents

How does the temperature of the fractionating column change as you move from bottom to top?

the temperature decreases

What happens when crude oil is heated before entering the fractionating column?

the crude oil evaporates

What happens to the crude oil vapours as they travel up the fractionating column?

• they cool and condense • when they condense they are collected

Describe how crude oil is seperated in fractional distillation

• Crude oil is heated and it evaporates • The crude oil vapours enter the fractionating column and travel upwards • The temperature of the fractionating column decreases towards the top • As the vapours travel up they cool and condense at different temperatures depending on their boiling points

Where are the long chain hydrocarbons collected in fractional distillation?

At the bottom of the fractionating column

Where are the short chain hydrocarbons collected in fractional distillation?

At the top of the fractionating column

What causes the hydrocarbons to sepeate in fractional distillation?

They have different boiling points and so condense at different levels

When will the hydrocarbons condense in the fractionating column?

When the temperature drops below their boiling point

Why do large chain hydrocarbons collect at the bottom of the fractionating column?

They have large boiling points and so condense at higher temperatures

Why do short chain hydrocarbons collect at the top of the fractionating column?

They have low boiling points and so condense at lower temperatures

If a hydrocarbon boils at 300 ᵒC, what temperature will it condense at?

300 ᵒC

What type of force holds hydrocarbon molecules together?

Intermolecular forces

What bonds break when hydrocarbons melt and boil?

Intermolecular forces

What does viscosity it mean?

How much a fluid resists flow (how gloopy it is)

What does volatility mean?

How easy it is to turn a substance into a gas

What does flammability mean?

How easy it is to ignite a substance

As hydrocarbon molecules get bigger, what happens to their viscosity?

increases

As hydrocarbon molecules get bigger, what happens to the boiling point?

increases

As hydrocarbon molecules get bigger, what happens to their flammability?

decreases

Why does the boiling point of hydrocarbons increase as the hydrocarbon molecules get bigger?

As the hydrocarbon molecules get bigger, the intermolecular forces get stronger and require more energy to break

Why does the viscosity of hydrocarbons increase as the hydrocarbon molecules get bigger?

As the hydrocarbon molecules get bigger, the intermolecular forces get stronger and move over each other less easily

Which are better fuels - long or short chain hydrocarbons?

Short chain (they are more flammable)

What is combustion?

reaction with oxygen (burning)

What is complete combustion?

burning in a plentiful supply of oxygen

What are the reactants in complete combustion of a hydrocarbon?

hydrocarbon + oxygen

What are the products in complete combustion of a hydrocarbon?

carbon dioxide + water

What is cracking?

the breaking of longer chain hydrocarbons into shorter, more useful hydrocarbons

Why do we 'crack' hydrocarbons?

to produce smaller, more useful molecules

What is the reactant in cracking?

longer chain alkanes

What are the products in cracking?

a shorter chain alk𝗮𝗻𝗲 and a short chain alk𝗲𝗻𝗲

What is thermal decomposition?

the breakdown of a substance when it is heated

Why is cracking a thermal decomposition reaction?

the longer chain hydrocarbons breakdown when heated

Name two types of cracking

• steam • catalytic cracking

Describe the process of steam cracking

• Long chain hydrocarbons are heated and they evaporate • The hydrocarbon vapour is heated to a very high temperature and mixed with steam • The hydrocarbons are broken into smaller hydrocarbons

Describe the process of catalytic cracking

• Long chain hydrocarbons are heated and they evaporate • The hydrocarbon vapour is then passed over a catalyst • The hydrocarbons are broken into smaller hydrocarbons

Which are more reactive: alkanes or alkenes?

Alkenes

What is used to test for alkenes?

bromine water

What colour is bromine water?

orange

What colour does bromine water turn when added to alkenes?

colourless

What colour does bromine water turn when added to alkanes?

stays orange

What are alkenes used for?

to make polymers and as the starting material when making many other chemicals

What are alkenes?

Hydrocarbons with a double carbon-carbon bond

What is the general formula for alkenes?

CₙH₂ₙ

Are alkenes saturated or unsaturated?

Unsaturated

What are the first four members of the homologous series of alkenes?

Ethene, propene, butene and pentene

Why do alkenes produce smokey flames when they react with oxygen?

Incomplete combustion

What happens to the double bond when alkenes react with water, hydrogen and the halogens?

It becomes a single bond

What functional group do alcohols contain?

-OH

What are the first four members of the homologous series of alcohols?

Methanol, ethanol, propanol and butanol

What solutions are produced when sugar solutions are fermented with yeast?

Aqueous solutions of ethanol

What are the conditions for the fermentation of sugar using yeast?

• sugars dissolved in water, and mixed with yeast • an air lock to allow carbon dioxide out, while stopping air getting in • warm temperature , 25-35°C

What happens when alcohol reacts with sodium?

Bubbles of hydrogen gas are produced and the liquid contains sodium ethoxide

What happens when alcohol reacts with air?

They can oxidise with complete/incomplete combustion OR they can oxidise without combustion to produce carboxylic acid

What happens to the solubilty of alcohol in water as the hydrocarbon chain gets longer?

The longer the chain the less soluble the alcohol

What functional group do carboxylic acids have?

-COOH

What are the first four members of the homologous series of carboxylic acids?

Methanoic acid, ethanoic acid, propanoic acid and butanoic acid

What happens when carboxylic acids reacts with carbonates?

Salt, water and carbon dioxide are produced

What happens when carboxylic acids dissolve in water?

Solutions with a pH of less than 7 are formed

What happens when carboxylic acids react with alcohols?

Esters are produced

What functional group to esters contain?

-COO

What is the structural formula for methanol?

CH₃OH

What is the structural formula for ethanol?

CH₃CH₂OH

What is the structural formula for propanol?

CH₃CH₂CH₂OH

What is the structural formula for butanol?

CH₃CH₂CH₂CH₂OH

What is the structural formula for methanoic acid?

HCOOH

What is the structrual formula for ethanoic acid?

CH₃COOH

What is the structural formual for propanoic acid?

CH₃CH₂COOH

What is the structural formual for butanoic acid?

CH₃CH₂CH₂COOH

By what process can alkenes be used to make polymers?

Addition polymerisation

What happens during addition polymerisation?

Many small molecules (monomers) join together to form very large molecules (polymers)

What are polymers?

A substance of high relative formula mass, made up of small repeating units

What happens during condensation polymerisation?

Monomers with two functional groups react together, losing small molecules such as water

How are polypeptides produced?

Amino acids react through condensation polymerisation

How many functional groups do amino acids contain?

Two

What are some examples of naturally occuring polymers?

DNA, proteins, starch and cellulose

What is the polymer for DNA made from?

Four different types of monomer (nucleotides) that form two polymer chains which twist around each other (double helix)

What monomers are proteins made from ?

Amino acid monomers

What monomers are starch and cellulose made from?

Sugar molecule monomers