mix of everything - AS AQA

The crude oil is heated in a furnace.

A mixture of liquid and vapour passes into a tower that is cooler at the top than at the bottom.

The vapour travels up the tower via a series of trays containing bubble caps until they arrive at a tray that is sufficiently cool. Then they condense to a liquid.

The mixtures of liquids that condense in the trays are piped off. The shorter chained hydrocarbons condense in the trays nearer the top as they have low boiling points. 

the thick residue that collects at the bottom of the tower is called tar or bitumin. it can be used for road surfacing but as supply exceeps demand this is often further processed to give more valuable products.

-- Carbohydrates are broken down into sugars, and then converted to ethanol by yeast. 

C₆H₁₂O_{6 (Aq)} à 2C₂H₅OH _(Aq) + 2CO_{2 (g)}  

- - Rate of reactions is affected by temperature

  - Air is kept out. So ethanol DOESN’T turn into ethanoic acid. 

Advantages:

-Can be classed as carbon neutral

-Renewable source

Disadvantages:

-Releases CO2 when burned

-Land could be used for food production instead

-Time consuming

-Expensive to carry out all of the processes needed

Ethane is produced when crude oil fractions are cracked

Ethane is hydrated. The water is added across the double bond

                     (Phosphoric acid)

CH₂=CH₂ + H₂O      à   C₂H₅OH

Conditions of 570K and 6500KPa pressure are used

It’s reversible!

Waste: none 

Enviromental issues: - Ethene obtained through cracking.

                                         - Energy used for cracking alkanes.

Economics: - High pressure - High energy costs.

                       - High temperature - High energy costs.

                       - Costs linked to cost of crude oil.

ENDOTHERMIC: Energy is taken in!

EXOTHERMIC: Energy is given out!

         Mr = average mass of one molecule

          ¹/₁₂ mass of an atom of ¹²C

We find the relative molecular mass by adding up the relative atomic masses of all the atoms present in the molecule and we find this from the above formula.

If asked to define relative molecular mass simply state the formula and you won’t go wrong.

These are pentane and two of  its branched isomers: 

Most organic compounds are made of a hydrocarbon chain that has one or more reactive groups attached to it. We call these reactive groups Functional Groups.

The functional Group reacts in the same way, whatever the length of the hydrocarbon chain.

Functional groups are named by using a suffix or prefix.

Number of Carbons

Root

1

Meth

2

Eth

3

Prop

4

But

5

Pent

6

Hex

The first six roots in the naming of organic compounds.

                                 Mass of useful product

Atom Economy = ----------------------------------  X100

                                Total mass of reactants

Example:

N2 +3H2 à 2NH3

34

----  X 100  = 100%

34

To increase the amount of useful product you leave to sell the spare products.

What happes in a mass spectrometer? 

Atoms are converted into ions, accelerated and deflected according to their masses and their charges and then arrive at a detector. 

The sample has to be in a gaseous state. if it is a solid it is first vapourised by heating.

Ionisation

A beam of electrons from an ‘electron gun’ knocks out electrons from atoms or molecules of the sample so that they form positive ions.

Nearly all the atoms or molecules lose just one electron and form ions with a 1+ charge but a small number lose two electrons to form a 2+ charge.

Acceleration

These positive ions are attracted towards negatively charged plates and are accelerated to high speeds. The speed they reach depends on their mass. The lighter ions, the faster they go.

Some ions pass through slits in the plates. This forms the ions into a beam.

Deflection

The beams of ions then move into a magnetic field at right angles to its direction of travel. The magnetic field deflects the beam of ions into an arc of a circle.

The deflection of an ion depends on its mass. Heavier ions are deflected less than lighter ones and 2+ ions are deflected twice as much as 1+ ion’s with the same mass.

The deflection also depends on the magnetic field strength – the stronger the field, the greater the deflections. 

Detection

The magnetic field is gradually increased so that ions of increasing mass enter the detector one after another. Ion’s strike the detector, accept electrons, lose their charge and create a current which is proportional to the abundance of each ion.

PV=nRT

P – Pressure (Pa)

V – Volume (m3)

n – Number of moles

R – Universal gas equation (8.31)

T – Temperature (K)

An isotope is an atom with the same number of protons and electrons but a different number of neutrons.

All isotopes from an element have similar chemical properties; this is because chemical properties are determined by the number of electrons not the number of neutrons.

Is the simplest whole number ratio of the elements in a compound.

The energy required to break one mole of gaseous bonds to form gaseous atoms.

A covalent bond where the shared pair of electrons is displaced to one end. 

The ability of an atom to attract the pair of electrons in a covalent bond to itself.

The enthalpy change of a reaction is independant of the path taken.

The enthalpy change when one mole of a compound is formed in its standard state from its elements in their standard states. 

The enthalpy change when one mole of a substance undergoes complete combustion in its standard state.

The enthalpy change when one mole of a substance undergoes complete combustion in its standard state.

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions.

E.g.    Mg_(g) à Mg⁺_(g)  +  e^-